Carbazole Derivative, and Light-Emitting Element, Light-Emitting Device, and Electronic Device Using Carbazole Derivative

ABSTRACT

To provide a light-emitting element having high luminous efficiency and to provide a light-emitting device and an electronic device which consumes low power and is driven at low voltage, a carbazole derivative represented by the general formula (1) is provided. In the formula, α 1 , α 2 , α 3 , and α 4  each represent an arylene group having less than or equal to 13 carbon atoms; Ar 1  and Ar 2  each represent an aryl group having less than or equal to 13 carbon atoms; R 1  represents any of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, and a substituted or unsubstituted biphenyl group; and R 2  represents any of an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, and a substituted or unsubstituted biphenyl group. In addition, l, m, and n are each independently 0 or 1.

TECHNICAL FIELD

The present invention relates to a carbazole derivative, alight-emitting element, a light-emitting device, and an electronicdevice using a carbazole derivative.

BACKGROUND ART

In recent years, light-emitting elements using electroluminescence havebeen actively researched and developed. As a basic structure of theselight-emitting elements, a layer containing a light-emitting substanceis interposed between a pair of electrodes. By applying voltage to thiselement, light emission can be obtained from the light-emittingsubstance.

Since such a light-emitting element is a self-luminous type, it hasadvantages over a liquid crystal display element, such as highvisibility of the pixels and no need of backlight and is consideredsuitable for a flat panel display element. In addition, such alight-emitting element can be manufactured to be thin and light-weight,which is also a great advantage. Further, extremely high response speedis also a feature thereof.

Furthermore, since such a light-emitting element can be formed into afilm form, planar light emission can be easily obtained by forming alarge-area element. It is difficult to obtain this characteristic byusing a point light source typified by an incandescent lamp or an LED orby using a line light source typified by a fluorescent lamp. Therefore,the light-emitting element described above also has a high utility valueas a planar light source which is applicable to lighting or the like.

Such light-emitting elements using electroluminescence are broadlyclassified according to whether a light-emitting substance is an organiccompound or an inorganic compound. When an organic compound is used fora light-emitting substance, electrons and holes are injected into alayer containing a light-emitting organic compound from a pair ofelectrodes by applying voltage to a light-emitting element, and then acurrent flows therethrough. Then, by recombination of these carriers(electrons and holes), the light-emitting organic compound forms anexcited state, and emits light when the excited state returns to aground state.

With such a mechanism, such a light-emitting element is referred to as acurrent-excitation light-emitting element. Note that an excited state ofan organic compound can be a singlet excited state or a triplet excitedstate. Light emission from the singlet excited state is referred to asfluorescence, and light emission from the triplet excited state isreferred to as phosphorescence.

In improving element characteristics of such a light-emitting element,there are a lot of problems which depend on a substance, and in order tosolve the problems, improvement of an element structure, development ofa substance, and the like have been carried out (e.g., Non-PatentDocument 1: Meng-Huan Ho, Yao-Shan Wu and Chin H. Chen, 2005 SIDInternational Symposium Digest of Technical Papers, Vol. XXXVI. pp.802-805).

In the light-emitting element described in Non-Patent Document 1,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) isused as a layer in contact with a light-emitting layer. However, NPB haslow singlet excitation energy, and there is a possibility that theenergy might be transferred from the light-emitting material in theexcited state. Since the energy level of an excited state isparticularly high in the case of a light-emitting material which emitsblue light having a short wavelength, there is a higher possibility thatthe energy is transferred to NPB. There has been a problem that luminousefficiency of the light-emitting element is lowered due to transfer ofthe energy to NPB.

DISCLOSURE OF THE INVENTION

Thus, it is an object of the present invention to provide alight-emitting element having high luminous efficiency by providing anovel carbazole derivative. Further, it is another object of the presentinvention to provide a light-emitting device and an electronic devicewhich consumes low power and is driven at low voltage.

One feature of the present invention is a carbazole derivativerepresented by the following general formula (1).

In the formula, α¹, α², α³, and α⁴ each represent an arylene grouphaving less than or equal to 13 carbon atoms, which forms a ring; Ar¹and Ar² each represent an aryl group having less than or equal to 13carbon atoms, which forms a ring; R¹ represents any of a hydrogen atom,an alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted phenyl group, and a substituted or unsubstituted biphenylgroup; and R² represents any of an alkyl group having 1 to 6 carbonatoms, a substituted or unsubstituted phenyl group, and a substituted orunsubstituted biphenyl group. In addition, l, m, and n are eachindependent, which is 0 or 1.

In addition, in the above structure, α¹ to α⁴ in the general formula (1)are represented by any of the following general formulas (2-1) to(2-12).

In the formula, R¹ to R¹⁶, R²¹ to R³⁰, R³¹ to R³⁸, and R⁴¹ to R⁴⁵ eachrepresent any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group. R⁴⁶ and R⁴⁷ each representany of an alkyl group having 1 to 6 carbon atoms and a phenyl group. Inaddition, R⁴⁶ and R⁴⁷ may be connected to each other to form a ring. R⁴⁸represents any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group.

In addition, in the above structure, Ar¹ and Ar² in the general formula(1) are represented by any of the following general formulas (3-1) to(3-6).

In the formula, R⁵¹ to R⁵⁶, R⁶¹ to R⁷⁰, R⁷¹ to R⁷⁸, and R⁸¹ to R⁸⁵ eachrepresent any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group. R⁸⁶ and R⁸⁷ each representany of an alkyl group having 1 to 6 carbon atoms and a phenyl group. Inaddition, R⁸⁶ and R⁸⁷ may be connected to each other to form a ring. R⁸⁸and R⁸⁹ each represent any of a hydrogen atom, an alkyl group having 1to 6 carbon atoms, a phenyl group, and a biphenyl group.

Further, in the above structure, R¹ in the general formula (1) isrepresented by any of the following general formulas (4-1) to (4-9), andR² in the general formula (1) is represented by any of the followinggeneral formulas (4-2) to (4-9).

In the formula, R⁵¹ to R⁷⁰ each represent any of a hydrogen atom, analkyl group having 1 to 6 carbon atoms, a phenyl group, and a biphenylgroup.

In addition, one feature of the present invention is represented by anyof the following structural formulas (5) to (8).

In addition, as another feature of the present invention, alight-emitting element includes an EL layer between a pair ofelectrodes, the EL layer includes at least a light-emitting layer and ahole-transporting layer, and at least one of the light-emitting layerand the hole-transporting layer contains any of the carbazolederivatives described above.

Further, as another feature of the present invention, a light-emittingelement includes an EL layer between an anode and a cathode, the ELlayer includes at least a light-emitting layer, a hole-transportinglayer, and a hole-injecting layer, the hole-injecting layer is formed incontact with the anode, and at least one of the light-emitting layer,the hole-transporting layer, and the hole-injecting layer contains anyof the carbazole derivatives described above.

In addition, in the above structure, a structure may be employed inwhich the hole-injecting layer contains any of the carbazole derivativesdescribed above and an inorganic compound which exhibits anelectron-accepting property with respect to the carbazole derivative.Note that as the inorganic compound, an oxide of a transition metal canbe used. Further, as the inorganic compound, one or more kinds oftitanium oxide, vanadium oxide, molybdenum oxide, tungsten oxide,rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafniumoxide, tantalum oxide, and silver oxide can be used.

Further, as another feature of the present invention, a light-emittingdevice is formed using any of the light-emitting elements describedabove, and an electronic device is formed using the light-emittingdevice.

Further, the present invention also includes a light-emitting devicehaving the light-emitting element described above and an electronicdevice having the light-emitting device. A light-emitting device in thisspecification refers to an image display device, a light-emittingdevice, or a light source (including a lighting device). In addition,light-emitting devices include all of the following modules: modules inwhich a connector, for example, a flexible printed circuit (FPC), a tapeautomated bonding (TAB) tape, or a tape carrier package (TCP) isattached to a light-emitting device; modules provided with a printedwiring board at the end of a TAB tape or a TCP; and modules where anintegrated circuit (IC) is directly mounted on a light-emitting elementby a chip-on-glass (COG) method.

Since the carbazole derivative of the present invention exhibits a highhole-transporting property, it can be mainly used for ahole-transporting layer which is included in an EL layer of alight-emitting element. In addition, the carbazole derivative of thepresent invention is used for the hole-transporting layer to form alight-emitting element, whereby a light-emitting element having highluminous efficiency can be formed.

Further, a light-emitting device and an electronic device which consumeslow power and is driven at low voltage can be obtained by using thislight-emitting element.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are cross-sectional views each showing a stacked-layerstructure of a light-emitting element in Embodiment Mode 2;

FIGS. 2A to 2C are cross-sectional views each showing a mode of lightemission of a light-emitting element in Embodiment Mode 2;

FIG. 3 is a cross-sectional view showing a stacked-layer structure of alight-emitting element in Embodiment Mode 3;

FIGS. 4A and 4B are respectively a top view and a cross-sectional viewof an active matrix light-emitting device in Embodiment Mode 4;

FIGS. 5A and 5B are respectively a perspective view and across-sectional view of a passive matrix light-emitting device inEmbodiment Mode 4;

FIGS. 6A to 6D are views each showing an electronic device in EmbodimentMode 5;

FIG. 7 is a view showing a liquid crystal display device using alight-emitting device of the present invention as a backlight;

FIG. 8 is a view showing a table lamp using a light-emitting device ofthe present invention;

FIG. 9 is a view showing an indoor lighting device using alight-emitting device of the present invention;

FIGS. 10A and 10B are graphs showing ¹H NMR charts of PCBA1BP(abbreviation);

FIGS. 11A and 11B are graphs showing an absorption spectrum and anemission spectrum of PCBA1BP (abbreviation);

FIGS. 12A and 12B are graphs showing ¹H NMR charts of PCBBi1BP(abbreviation);

FIGS. 13A and 13B are graphs showing an absorption spectrum and anemission spectrum of PCBBi1BP (abbreviation);

FIGS. 14A and 14B are graphs showing ¹H NMR charts of PCBAF(abbreviation);

FIGS. 15A and 15B are graphs showing an absorption spectrum and anemission spectrum of PCBAF (abbreviation);

FIGS. 16A and 16B are graphs showing ¹H NMR charts of PCBASF(abbreviation);

FIGS. 17A and 17B are graphs showing an absorption spectrum and anemission spectrum of PCBASF (abbreviation);

FIG. 18 is a cross-sectional view showing an element structure of alight-emitting element in Embodiment 5;

FIG. 19 is a graph showing the current density vs. luminancecharacteristics of a light-emitting element 1 and a light-emittingelement 2;

FIG. 20 is a graph showing the voltage vs. luminance characteristics ofthe light-emitting element 1 and the light-emitting element 2;

FIG. 21 is a graph showing the luminance vs. current efficiencycharacteristics of the light-emitting element 1 and the light-emittingelement 2;

FIG. 22 is a graph showing the voltage vs. current characteristics ofthe light-emitting element 1 and the light-emitting element 2;

FIG. 23 is a graph showing emission spectra of the light-emittingelement 1 and the light-emitting element 2;

FIG. 24 is a graph showing the result of a continuous lighting test ofthe light-emitting element 1 and the light-emitting element 2 byconstant current driving;

FIG. 25 is a graph showing the current density vs. luminancecharacteristics of the light-emitting element 1 and a light-emittingelement 3;

FIG. 26 is a graph showing the voltage vs. luminance characteristics ofthe light-emitting element 1 and the light-emitting element 3;

FIG. 27 is a graph showing the luminance vs. current efficiencycharacteristics of the light-emitting element 1 and the light-emittingelement 3;

FIG. 28 is a graph showing the voltage vs. current characteristics ofthe light-emitting element 1 and the light-emitting element 3;

FIG. 29 is a graph showing emission spectra of the light-emittingelement 1 and the light-emitting element 3;

FIG. 30 is a graph showing the current density vs. luminancecharacteristics of the light-emitting element 1 and a light-emittingelement 4;

FIG. 31 is a graph showing the voltage vs. luminance characteristics ofthe light-emitting element 1 and the light-emitting element 4;

FIG. 32 is a graph showing the luminance vs. current efficiencycharacteristics of the light-emitting element 1 and the light-emittingelement 4;

FIG. 33 is a graph showing the voltage vs. current characteristics ofthe light-emitting element 1 and the light-emitting element 4;

FIG. 34 is a graph showing emission spectra of the light-emittingelement 1 and the light-emitting element 4;

FIG. 35 is a graph showing the result of a continuous lighting test ofthe light-emitting element 1 and the light-emitting element 4 byconstant current driving;

FIG. 36 is a graph showing the current density vs. luminancecharacteristics of the light-emitting element 1 and a light-emittingelement 5;

FIG. 37 is a graph showing the voltage vs. luminance characteristics ofthe light-emitting element 1 and the light-emitting element 5;

FIG. 38 is a graph showing the luminance vs. current efficiencycharacteristics of the light-emitting element 1 and the light-emittingelement 5;

FIG. 39 is a graph showing the voltage vs. current characteristics ofthe light-emitting element 1 and the light-emitting element 5;

FIG. 40 is a graph showing emission spectra of the light-emittingelement 1 and the light-emitting element 5;

FIG. 41 is a graph showing CV characteristics of PCBA1BP (abbreviation);

FIG. 42 is a graph showing CV characteristics of PCBBi1BP(abbreviation);

FIG. 43 is a graph showing CV characteristics of PCBAF (abbreviation);

FIG. 44 is a graph showing CV characteristics of PCBASF (abbreviation);

FIGS. 45A and 45B are graphs showing ¹H NMR charts of PCTA1BP(abbreviation);

FIGS. 46A and 46B are graphs showing ¹H NMR charts of PCTBi1BP(abbreviation);

FIGS. 47A and 47B are graphs showing ¹H NMR charts of PCBANB(abbreviation);

FIGS. 48A and 48B are graphs showing ¹H NMR charts of PCBNBB(abbreviation);

FIGS. 49A and 49B are graphs showing ¹H NMR charts of PCBBiNB(abbreviation);

FIGS. 50A and 50B are graphs showing ¹H NMR charts of PCBANT(abbreviation);

FIGS. 51A and 51B are graphs showing ¹H NMR charts of BCBA1BP(abbreviation);

FIGS. 52A and 52B are graphs showing ¹H NMR charts of BCBANB(abbreviation);

FIGS. 53A and 53B are graphs showing ¹H NMR charts of BCBBiNB(abbreviation);

FIGS. 54A and 54B are graphs showing ¹H NMR charts of NBCBA1BP(abbreviation);

FIGS. 55A and 55B are graphs showing ¹H NMR charts of NCBA1BP(abbreviation);

FIG. 56 is a graph showing the voltage vs. luminance characteristics ofthe light-emitting element 1 and light-emitting elements 6 to 8;

FIG. 57 is a graph showing the luminance vs. current efficiencycharacteristics of the light-emitting element 1 and the light-emittingelements 6 to 8;

FIG. 58 is a graph showing the voltage vs. current characteristics ofthe light-emitting element 1 and the light-emitting elements 6 to 8;

FIG. 59 is a graph showing emission spectra of the light-emittingelement 1 and the light-emitting elements 6 to 8;

FIG. 60 is a graph showing the result of a continuous lighting test ofthe light-emitting element 1 and the light-emitting elements 6 to 8 byconstant current driving;

FIGS. 61A and 61B are graphs showing ¹H NMR charts of PCBBi1BPIII(abbreviation);

FIGS. 62A to 62C are graphs showing ¹H NMR charts of PCBA1BPIV(abbreviation);

FIGS. 63A and 63B are graphs showing ¹H NMR charts of PCBNBBβ(abbreviation); and

FIGS. 64A and 64B are graphs showing ¹H NMR charts of PCBBiFLP(abbreviation).

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiment modes and embodiments according to the present inventionwill hereinafter be described in detail with reference to the drawings.However, the present invention is not limited to description to be givenbelow, and it is to be easily understood that modes and details thereofcan be variously modified without departing from the purpose and thescope of the present invention. Thus, the present invention is notinterpreted while limiting to the following description of theembodiment modes and embodiments.

Embodiment Mode 1

In Embodiment Mode 1, a carbazole derivative of the present inventionwill be described.

The carbazole derivative of the present invention is represented by ageneral formula (1).

In the formula, α¹, α², α³, and α⁴ each represent an arylene grouphaving less than or equal to 13 carbon atoms, which forms a ring; Ar¹and Ar² each represent an aryl group having less than or equal to 13carbon atoms, which forms a ring; R¹ represents any of a hydrogen atom,an alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted phenyl group, and a substituted or unsubstituted biphenylgroup; and R² represents any of alkyl group having 1 to 6 carbon atoms,a substituted or unsubstituted phenyl group, and a substituted orunsubstituted biphenyl group. In addition, l, m, and n are eachindependent, which is 0 or 1.

In the general formula (1), α¹ to α⁴ each represent an arylene grouphaving less than or equal to 13 carbon atoms, which forms a ring.Specifically, substituents represented by structural formulas (2-1) to(2-12) can be given.

In the formula, R¹¹ to R¹⁶, R²¹ to R³⁰, R³¹ to R³⁸, and R⁴¹ to R⁴⁵ eachrepresent any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group. R⁴⁶ and R⁴⁷ each representany of an alkyl group having 1 to 6 carbon atoms and a phenyl group. Inaddition, R⁴⁶ and R⁴⁷ may be connected to each other to form a ring. R⁴⁸represents any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group.

In the general formula (1), Ar¹ and Ar² each represent an aryl grouphaving less than or equal to 13 carbon atoms, which forms a ring.Specifically, substituents represented by structural formulas (3-1) to(3-6) can be given.

In the formula, R⁵¹ to R⁵⁶, R⁶¹ to R⁷⁰, R⁷¹ to R⁷⁸, and R⁸¹ to R⁸⁵ eachrepresent any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group. R⁸⁶ and R⁸⁷ each representany of an alkyl group having 1 to 6 carbon atoms and a phenyl group. Inaddition, R⁸⁶ and R⁸⁷ may be connected to each other to form a ring. R⁸⁸and R⁸⁹ each represent any of a hydrogen atom, an alkyl group having 1to 6 carbon atoms, a phenyl group, and a biphenyl group.

In the general formula (1), R¹ represents any of a hydrogen atom, analkyl group having 1 to 6 carbon atoms, a substituted or unsubstitutedphenyl group, and a substituted or unsubstituted biphenyl group; and R²represents any of an alkyl group having 1 to 6 carbon atoms, asubstituted or unsubstituted phenyl group, and a substituted orunsubstituted biphenyl group. Specifically, substituents represented bystructural formulas (4-1) to (4-9) can be given for R¹, and thesubstituents represented by the structural formulas (4-2) to (4-9) canbe given for R².

In the formula, R⁵¹ to R⁷⁰ each represent any of a hydrogen atom, analkyl group having 1 to 6 carbon atoms, a phenyl group, and a biphenylgroup.

As a specific example of the carbazole derivatives of the presentinvention represented by the general formula (1), carbazole derivativesrepresented by structural formulas (9) to (425) can be given. However,the present invention is not limited thereto.

In addition, the carbazole derivative of the present inventionrepresented by the general formula (1) can be synthesized by a syntheticmethod represented by the following synthetic schemes (A-1) to (A-7), asynthetic scheme (B-1), and synthetic schemes (C-1) to (C-2).

[Synthetic Method of Halogenated Secondary Arylamine (Compound A)]

Halogenated secondary arylamine represented by a general formula(compound A) can be synthesized in a manner like the following syntheticscheme (A-1). In other words, first, secondary arylamine (compound A₁)is halogenated by using a halogenating agent, whereby the halogenatedsecondary arylamine (compound A) can be obtained. Note that as thehalogenating agent, N-bromosuccinimide (NBS), N-iodosuccinimide (NIS),bromine, iodine, potassium iodide, or the like can be used. In addition,each X¹ represents a halogen group, which is preferably a bromo group oran iodine group.

[Synthetic Method of a Halogenated Carbazole Derivative (Compound B₂)]

A halogenated carbazole derivative represented by a general formula(compound B₂) can be synthesized in a manner like the followingsynthetic scheme (A-2). In other words, first, a carbazole derivative(compound B₁) is halogenated by using a halogenating agent, whereby thehalogenated carbazole derivative (compound B₂) can be obtained. Notethat as the halogenating agent, N-bromosuccinimide (NBS),N-iodosuccinimide (NIS), bromine, iodine, potassium iodide, or the likecan be used. In addition, each X¹ represents a halogen group, which ispreferably a bromo group or an iodine group.

[Synthetic Method of a Compound (Compound B) in which9H-carbazol-3-boronic Acid or the Third Position of 9H-carbazol isSubstituted by Organoboron]

A compound in which the third position of 9H-carbazole is substituted byboronic acid or organoboron, which is represented by a general formula(compound B), can be synthesized in a manner like the followingsynthetic scheme (A-3). In other words, boron oxidation ororganoboronation is performed on the halogenated carbazole derivative(compound B₂) using an alkyllithium reagent and a boron reagent, wherebythe compound in which the third position of 9H-carbazole is substitutedby boronic acid or organoboron (compound B) can be obtained.

Note that R⁹⁹ in the scheme (A-3) represents an alkyl group having 1 to6 carbon atoms. R⁹⁸ presents an alkyl group having 1 to 6 carbon atoms.In addition, R¹⁰⁰ and R^(10l) each represent a hydrogen atom or an alkylgroup having 1 to 6 carbon atoms. R¹⁰² and R¹⁰³ may be connected to eachother to form a ring. In addition, n-butyllithium, methyllithium, or thelike can be used as the alkyllithium reagent. Trimethyl borate,isopropyl borate, or the like can be used as the boron reagent.

[Synthetic Method of Secondary Arylamine (Compound C₃)]

Secondary arylamine represented by a general formula (compound C₃) canbe synthesized in a manner like the following synthetic scheme (A-4). Inother words, halogenated aryl (compound Cl) and primary arylamine(compound C₂) are coupled in the presence of a base using a metalcatalyst, whereby the secondary arylamine (compound C₃) can be obtained.

In the case where a Buchwald-Hartwig reaction is performed, as thepalladium catalyst which can be used in the synthetic scheme (A-4),although bis(dibenzylideneacetone)palladium(0), palladium(II) acetate,and the like can be given, the palladium catalyst which can be used isnot limited thereto. As a ligand in the palladium catalyst which can beused in the synthetic scheme (A-4), although tri(tert-butyl)phosphine,tri(n-hexyl)phosphine, tricyclohexylphosphine, and the like can begiven, the ligand which can be used is not limited thereto.

As a base which can be used in the synthetic scheme (A-4), although anorganic base such as sodium tert-butoxide, an inorganic base such aspotassium carbonate, and the like can be given, the base which can beused is not limited thereto. In addition, as a solvent that can be usedin the synthetic scheme (A-4), although toluene, xylene, benzene,tetrahydrofuran, and the like can be given, the solvent which can beused is not limited thereto.

The case in which an Ullmann reaction is performed in the syntheticscheme (A-4) is described. In the synthetic scheme (A-4), R¹⁰⁴ and R¹⁰⁵each represent a halogen group, an acetyl group, or the like, andchlorine, bromine, and iodine can be given as the halogen group. It ispreferable that R¹⁰⁴ be iodine to form copper(I) iodide or that R¹⁰⁵ bean acetyl group to form a copper(II) acetate. The copper compound usedfor the reaction is not limited thereto, and copper can be used as analternative to the copper compound. As a base which can be used in thesynthetic scheme (A-4), although an inorganic base such as potassiumcarbonate can be given, the base which can be used is not limitedthereto.

As a solvent which can be used in the synthetic scheme (A-4), although1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation: DMPU),toluene, xylene, benzene, and the like can be given, the solvent whichcan be used is not limited thereto. DMPU or xylene which has a highboiling point is preferably used because, by an Ullmann reaction, anobject can be obtained in a shorter time and at a higher yield when thereaction temperature is greater than or equal to 100° C. Since it isfurther preferable that the reaction temperature be a temperaturegreater than or equal to 150° C., DMPU is more preferably used.

[Synthetic Method of Tertiary Arylamine (Compound C₅)]

Tertiary arylamine represented by a general formula (compound C₅) can besynthesized in a manner like the following synthetic scheme (A-5). Inother words, the secondary arylamine (compound C₃) and halogenated aryl(compound C₄) are coupled in the presence of a base using a metalcatalyst, whereby the tertiary arylamine (compound C₅) can be obtained.

In the case where a Buchwald-Hartwig reaction is performed, as thepalladium catalyst which can be used in the synthetic scheme (A-5),although bis(dibenzylideneacetone)palladium(0), palladium(II) acetate,and the like can be given, the palladium catalyst which can be used isnot limited thereto. As a ligand in the palladium catalyst which can beused in the synthetic scheme (A-5), although tri(tert-butyl)phosphine,tri(n-hexyl)phosphine, tricyclohexylphosphine, and the like can begiven, the ligand which can be used is not limited thereto.

As a base which can be used in the synthetic scheme (A-5), although anorganic base such as sodium tert-butoxide, an inorganic base such aspotassium carbonate, and the like can be given, the base which can beused is not limited thereto. In addition, as a solvent that can be usedin the synthetic scheme (A-5), although toluene, xylene, benzene,tetrahydrofuran, and the like can be given, the solvent which can beused is not limited thereto.

The case in which an Ullmann reaction is performed in the syntheticscheme (A-5) is described. In the synthetic scheme (A-5), R¹⁰⁴ and R¹⁰⁵each represent a halogen group, an acetyl group, or the like, andchlorine, bromine, and iodine can be given as the halogen group. It ispreferable that R¹⁰⁴ be iodine to form copper(I) iodide or that R¹⁰⁵ bean acetyl group to form a copper(II) acetate. The copper compound usedfor the reaction is not limited thereto, and copper can be used as analternative to the copper compound. As a base which can be used in thesynthetic scheme (A-5), although an inorganic base such as potassiumcarbonate can be given, the base which can be used is not limitedthereto.

As a solvent which can be used in the synthetic scheme (A-5), although1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation: DMPU),toluene, xylene, benzene, and the like can be given, the solvent whichcan be used is not limited thereto. DMPU or xylene which has a highboiling point is preferably used because, by an Ullmann reaction, anobject can be obtained in a shorter time and at a higher yield when thereaction temperature is greater than or equal to 100° C. Since it isfurther preferable that the reaction temperature be a temperaturegreater than or equal to 150° C., DMPU is more preferably used.

[Synthetic Method of Tertiary Arylamine (Compound C₅)]

Tertiary arylamine represented by a general formula (compound C₅) can besynthesized in a manner like the following synthetic scheme (A-6). Inother words, the primary arylamine (compound C₂) and the halogenatedaryl (compounds C₁ and C₄) are coupled in the presence of a base using ametal catalyst, whereby the tertiary arylamine (compound C₅) can beobtained. However, when Ar¹ and Ar² are the same, β¹ and β² are thesame, and l and m are the same, the compound C₅ can be obtained withhigh yield.

In the case where a Buchwald-Hartwig reaction is performed, as thepalladium catalyst which can be used in the synthetic scheme (A-6),although bis(dibenzylideneacetone)palladium(0), palladium(II) acetate,and the like can be given, the palladium catalyst which can be used isnot limited thereto. As a ligand in the palladium catalyst which can beused in the synthetic scheme (A-6), although tri(tert-butyl)phosphine,tri(n-hexyl)phosphine, tricyclohexylphosphine, and the like can begiven, the ligand which can be used is not limited thereto.

As a base which can be used in the synthetic scheme (A-6), although anorganic base such as sodium tert-butoxide, an inorganic base such aspotassium carbonate, and the like can be given, the base which can beused is not limited thereto. In addition, as a solvent that can be usedin the synthetic scheme (A-6), although toluene, xylene, benzene,tetrahydrofuran, and the like can be given, the solvent which can beused is not limited thereto.

The case in which an Ullmann reaction is performed in the syntheticscheme (A-6) is described. In the synthetic scheme (A-6), R¹⁰⁴ and R¹⁰⁵each represent a halogen group, an acetyl group, or the like, andchlorine, bromine, and iodine can be given as the halogen group. It ispreferable that R¹⁰⁴ be iodine to form copper(I) iodide or that R¹⁰⁵ bean acetyl group to form a copper(II) acetate. The copper compound usedfor the reaction is not limited thereto, and copper can be used as analternative to the copper compound. As a base which can be used in thesynthetic scheme (A-6), although an inorganic base such as potassiumcarbonate can be given, the base which can be used is not limitedthereto.

As a solvent which can be used in the synthetic scheme (A-6), although1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation: DMPU),toluene, xylene, benzene, and the like can be given, the solvent whichcan be used is not limited thereto. DMPU or xylene which has a highboiling point is preferably used because, by an Ullmann reaction, anobject can be obtained in a shorter time and at a higher yield when thereaction temperature is greater than or equal to 100° C. Since it isfurther preferable that the reaction temperature be a temperaturegreater than or equal to 150° C., DMPU is more preferably used.

[Synthetic Method of Halogenated Tertiary Arylamine Derivative (CompoundC)]

Halogenated tertiary arylamine represented by a general formula(compound C) can be synthesized in a manner like the following syntheticscheme (A-7). In other words, first, tertiary arylamine (compound C₅) ishalogenated by using a halogenating agent, whereby the halogenatedtertiary arylamine (compound C) can be obtained. Note that as thehalogenating agent, N-bromosuccinimide (NBS), N-iodosuccinimide (NIS),bromine, iodine, potassium iodide, or the like can be used. In addition,each X¹ represents a halogen group, which is preferably a bromo group oran iodine group.

[Synthetic Method of Secondary Arylamine (Compound D)]

Secondary arylamine having carbazole, which is represented by a generalformula (compound D), can be synthesized in a manner like the followingsynthetic scheme (B-1). In other words, the halogenated secondaryarylamine (compound A) and the compound in which the third position of9H-carbazole is substituted by boronic acid or organoboron (compound B)can be coupled in the presence of a base using a metal catalyst.Accordingly, the secondary arylamine having carbazole (compound D) canbe obtained.

In any of the above schemes, the case of using a Suzuki-Miyaura reactionis described. As a palladium catalyst which can be used as a metalcatalyst, palladium(II) acetate,tetrakis(triphenylphosphine)palladium(0),bis(triphenylphosphine)palladium(II) dichloride, and the like can begiven. As a ligand in the above palladium catalyst,tri(ortho-tolyl)phosphine, triphenylphosphine, tricyclohexylphosphine,and the like can be given. In addition, as the above base, an organicbase such as sodium tert-butoxide, an inorganic base such as potassiumcarbonate, and the like can be given. As the solvent which can be used,a mixed solvent of toluene and water; a mixed solvent of toluene, analcohol such as ethanol, and water; a mixed solvent of xylene and water;a mixed solvent of xylene, an alcohol such as ethanol, and water; amixed solvent of benzene and water; a mixed solvent of benzene, analcohol such as ethanol, and water; a mixed solvent of ethers such asethyleneglycoldimethylether and water; and the like can be given.

However, the catalyst, ligand, base, and solvent which can be used arenot limited thereto.

In addition, in any of the above schemes, cross coupling usingorganoaluminum, organozirconium, organozinc, or organotin compound, orthe like, in addition to arylboronic acid, may be employed as a basematerial. However, the present invention is not limited thereto.

[Synthetic Method of Tertiary Arylamine Having Carbazole (Compound E)]

Tertiary arylamine having carbazole represented by a general formula(compound E) can be synthesized in a manner like the following syntheticscheme (C-1). In other words, the secondary arylamine having carbazole(compound D) and the halogenated aryl (compound C₄) are coupled in thepresence of a base using a metal catalyst, whereby the tertiaryarylamine having carbazole (compound E), which is a final product, canbe obtained.

In any of the above schemes, the case of using a Suzuki-Miyaura reactionis described. As a palladium catalyst which can be used as a metalcatalyst, palladium(II) acetate,tetrakis(triphenylphosphine)palladium(0),bis(triphenylphosphine)palladium(II) dichloride, and the like can begiven. As a ligand in the above palladium catalyst,tri(ortho-tolyl)phosphine, triphenylphosphine, tricyclohexylphosphine,and the like can be given. In addition, as the above base, an organicbase such as sodium tert-butoxide, an inorganic base such as potassiumcarbonate, and the like can be given. As the solvent which can be used,a mixed solvent of toluene and water; a mixed solvent of toluene, analcohol such as ethanol, and water; a mixed solvent of xylene and water;a mixed solvent of xylene, an alcohol such as ethanol, and water; amixed solvent of benzene and water; a mixed solvent of benzene, analcohol such as ethanol, and water; a mixed solvent of ethers such asethyleneglycoldimethylether and water; and the like can be given.

However, the catalyst, ligand, base, and solvent which can be used arenot limited thereto.

In addition, in any of the above schemes, cross coupling usingorganoaluminum, organic zirconium, organozinc, organozirconium,organotin, or the like, in addition to arylboronic acid, may be employedas a base material. However, the present invention is not limitedthereto.

[Another Synthetic Method of the Tertiary Arylamine Having Carbazole(Compound E)]

The tertiary arylamine having carbazole represented by the generalformula (compound E) can be synthesized in a manner like the followingsynthetic scheme (C-2). In other words, first, the halogenated tertiaryarylamine (compound C) and the compound in which the third position of9H-carbazole is substituted by boronic acid or organoboron (compound B)are coupled in the presence of a base using a metal catalyst, wherebythe tertiary arylamine having carbazole (compound E), which is a finalproduct, can be obtained.

Embodiment Mode 2

In Embodiment Mode 2, a light-emitting element which is formed using,for a hole-transporting layer, the carbazole derivative of the presentinvention described in Embodiment Mode 1 will be described.

The light-emitting element in Embodiment Mode 2 includes a firstelectrode which functions as an anode, a second electrode whichfunctions as a cathode, and an EL layer interposed between the firstelectrode and the second electrode. Note that the light-emitting elementin Embodiment Mode 2 can obtain light emission when voltage is appliedto each electrode so that the potential of the first electrode is higherthan that of the second electrode.

In addition, the EL layer of the light-emitting element in EmbodimentMode 2 includes in its structure a first layer (a hole-injecting layer),a second layer (a hole-transporting layer), a third layer (alight-emitting layer), a fourth layer (an electron-transporting layer),and a fifth layer (an electron-injecting layer), from the firstelectrode side.

A structure of the light-emitting element in Embodiment Mode 2 isdescribed with reference to FIGS. 1A and 1B. A substrate 101 is used asa support of the light-emitting element. For the substrate 101, glass,quartz, plastics, or the like can be used, for example.

Note that although the above substrate 101 may remain in alight-emitting device or an electronic device which is a productutilizing the light-emitting element of the present invention, thesubstrate 101 may only have a function as the support of thelight-emitting element in the manufacturing process of thelight-emitting element, without remaining in an end product.

For a first electrode 102 formed over the substrate 101, a metal, analloy, an electrically conductive compound, a mixture thereof, or thelike having a high work function (specifically, a work function of 4.0eV or more) is preferably used. Specifically, the following examples canbe given: indium tin oxide (ITO), indium tin oxide containing silicon orsilicon oxide, indium zinc oxide (IZO), and indium oxide containingtungsten oxide and zinc oxide. Besides, gold (Au), platinum (Pt), nickel(Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt(Co), copper (Cu), palladium (Pd), titanium (Ti), nitrides of the metalmaterials (e.g. titanium nitride), and the like can be given. However,in the present invention, a first layer 111 in an EL layer 103 which isformed in contact with the first electrode 102 is formed using acomposite material with which holes are easily injected regardless ofthe work function of the first electrode 102. Therefore, a variety ofknown methods can be used as long as it is a material that can serve asan electrode material (e.g., a metal, an alloy, an electricallyconductive compound, a mixture thereof, or the like, or an elementbelonging to Group 1 or 2 of the periodic table is also included).

A film of any of those materials is generally formed by a sputteringmethod. For example, indium zinc oxide (IZO) can be formed by asputtering method using a target in which 1 wt % to 20 wt % zinc oxideis added to indium oxide; and indium oxide containing tungsten oxide andzinc oxide can be formed by a sputtering method using a target in which0.5 wt % to 5 wt % tungsten oxide and 0.1 wt % to 1 wt % zinc oxide areadded to indium oxide. Alternatively, the first layer 111 may be formedby a vacuum evaporation method, an ink-jet method, a spin-coatingmethod, or the like.

Further, when a layer containing a composite material which will bedescribed later is used as a material used for the first layer 111formed in contact with the first electrode 102 in the EL layer 103formed over the first electrode 102, any of a variety of materials suchas metals, alloys, and electrically conductive compounds; a mixturethereof; or the like can be used as a substance used for the firstelectrode 102 regardless of their work functions. For example, aluminum(Al), silver (Ag), an alloy containing aluminum (AlSi), or the like canalso be used.

Furthermore, an element belonging to Group 1 or 2 of the periodic table,which is a low work function material, that is, an alkali metal such aslithium (Li) or cesium (Cs), an alkaline earth metal such as magnesium(Mg), calcium (Ca), or strontium (Sr), an alloy containing any of thesemetals (such as an MgAg alloy or an AlLi alloy), a rare-earth metal suchas europium (Eu) or ytterbium (Yb), an alloy containing such rare-earthmetals, or the like can also be used.

Note that in the case where the first electrode 102 is formed using analkali metal, an alkaline-earth metal, or an alloy thereof, a vacuumevaporation method or a sputtering method can be employed. Note that inthe case of using a silver paste or the like, a coating method, anink-jet method, or the like can be used.

For the EL layer 103 formed over the first electrode 102, a knownsubstance can be used, and any of a low molecular compound and amacromolecular compound can be used. Note that the substance used toform the EL layer 103 has not only a structure formed of only an organiccompound but also a structure partially containing an inorganiccompound.

For forming the EL layer 103, a hole-injecting layer containing asubstance having a high hole-injecting property, a hole-transportinglayer containing a substance having a high hole-transporting property, alight-emitting layer containing a light-emitting substance, anelectron-transporting layer containing a substance having a highelectron-transporting property, an electron-injecting layer containing asubstance having a high electron-injecting property, and the like arecombined with each other and stacked, as appropriate.

Note that in the EL layer 103 shown in FIG. 1A, the first layer (ahole-injecting layer) 111, a second layer (a hole-transporting layer)112, a third layer (a light-emitting layer) 113, a fourth layer (anelectron-transporting layer) 114, and a fifth layer (anelectron-injecting layer) 115 are sequentially stacked from the firstelectrode 102 side.

The first layer 111 which is a hole-injecting layer is a hole-injectinglayer containing a substance having a high hole-injecting property. Asthe substance having a high hole-injecting property, molybdenum oxide,titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromiumoxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide,tungsten oxide, manganese oxide, or the like can be used. Alternatively,as a low-molecular organic compound, a phthalocyanine-based compoundsuch as phthalocyanine (abbreviation: H₂Pc), copper(II) phthalocyanine(abbreviation: CuPc), or vanadyl phthalocyanine (abbreviation: VOPc) canbe given.

In addition, the following aromatic amine compounds which arelow-molecular organic compounds can also be given:4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA);4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA);4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB);4,4′-bis(N-{4-[N′-(3-methylphenyl)-N′-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD);1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B);3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1);3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2);3-[N-(1-naphtyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1); and the like. Note that the carbazolederivative of the present invention which is described in EmbodimentMode 1 can also be used in a similar manner.

Further, a macromolecular compound (an oligomer, a dendrimer, a polymer,or the like) can also be used. For example, macromolecular compoundssuch as poly(N-vinylcarbazole) (abbreviation: PVK);poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), andpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD) can be given. In addition, a macromolecular compound, to whichacid is added, such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS)or polyaniline/poly(styrenesulfonic acid) (abbreviation: PAni/PSS) canalso be used.

Alternatively, for the first layer 111, the composite material in whicha substance having an acceptor property is contained in a substancehaving a high hole-transporting property can be used. Note that by usingthe substance having a high hole-transporting property containing asubstance having an acceptor property, a material used to form anelectrode may be selected regardless of its work function. In otherwords, not only a material with a high work function but also a materialwith a low work function can be used as the first electrode 102. Suchcomposite materials can be formed by co-evaporation of a substancehaving a high hole-transporting property and a substance having anacceptor property. Note that in this specification, “composition” meansnot only a simple mixture of two materials but also a mixture of aplurality of materials in a condition where an electric charge is givenand received among the materials.

As an organic compound used for the composite material, variouscompounds such as an aromatic amine compound, a carbazole derivative,aromatic hydrocarbon, and a macromolecular compound (an oligomer, adendrimer, a polymer, or the like) can be used. The organic compoundused for the composite material is preferably an organic compound havinga high hole-transporting property. Specifically, a substance having ahole mobility of 10⁻⁶ cm²/Vs or more is preferably used. However, otherthan the above substances may be used as long as the substance has ahigher hole-transporting property than an electron-transportingproperty. The organic compound that can be used for the compositematerial is specifically shown below.

As an organic compound used for the composite material, for example, anaromatic amine compound such as MTDATA, TDATA, DPAB, DNTPD, DPA3B,PCzPCA1, PCzPCA2, PCzPCN1,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB orα-NPD), andN,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD); and a carbazole derivative such as4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB),9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA), and1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene can be given.Note that the carbazole derivative of the present invention which isdescribed in Embodiment Mode 1 can also be used in a similar manner.

In addition, the following aromatic hydrocarbon compounds can be given:2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA);2-tert-butyl-9,10-di(1-naphthyl)anthracene;9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA);2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA);9,10-di(2-naphthyl)anthracene (abbreviation: DNA);9,10-diphenylanthracene (abbreviation: DPAnth); 2-tert-butylanthracene(abbreviation: t-BuAnth); 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA);9,10-bis[2-(1-naphthyl)phenyl]-2-tert-butyl-anthracene;9,10-bis[2-(1-naphthyl)phenyl]anthracene;2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene; and the like.

Further, the following aromatic hydrocarbon compound compounds can alsobe given: 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene;9,9′-bianthryl; 10,10′-diphenyl-9,9′-bianthryl;10,10′-bis(2-phenylphenyl)-9,9′-bianthryl;10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl; anthracene;tetracene; rubrene; perylene; 2,5,8,11-tetra(tert-butyl)perylene;pentacene; coronene; 4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation:DPVBi); 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation:DPVPA); and the like.

As a substance having an acceptor property, organic compounds such as7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ) and chloranil, and a transition metal oxide can be given. Inaddition, oxides of metals belonging to Groups 4 to 8 of the periodictable can be given. Specifically, vanadium oxide, niobium oxide,tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide,manganese oxide, and rhenium oxide are preferable because of a highelectron-accepting property. Among these, molybdenum oxide is especiallypreferable because it is stable in the air and its hygroscopic propertyis low so that it can be easily treated.

Note that a composite material, which is formed using the abovemacromolecular compound such as PVK, PVTPA, PTPDMA, or Poly-TPD and theabove substance having an acceptor property, may be used for the firstlayer 111. Note that a composite material, which is formed combining thecarbazole derivative of the present invention which is described inEmbodiment Mode 1 with the above substance having an acceptor property,can also be used for the first layer 111.

The second layer 112 which is a hole-transporting layer is ahole-transporting layer containing a substance having a highhole-transporting property. Note that the carbazole derivative of thepresent invention which is described in Embodiment Mode 1 is used forthe second layer 112 in Embodiment Mode 2.

In addition, the carbazole derivative of the present invention which isdescribed in Embodiment Mode 1 can also be used for both the first layer111 and the second layer 112. In this case, an element can bemanufactured easily and material use efficiency can also be improved.Moreover, since energy diagrams of the first layer 111 and the secondlayer 112 are the same or similar, carriers can be transported easilybetween the first layer 111 and the second layer 112.

The third layer 113 is a light-emitting layer containing a substancehaving a high light-emitting property. For the third layer 113, any oflow molecular organic compounds given below can be used.

As a light-emitting substance for blue emission,N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation:YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA), and the like can be given.

As a light-emitting substance for green emission, the following can begiven: N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA);N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA);N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA);N-[9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA); N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA); and the like.

As a light-emitting substance for yellow light emission, rubrene,5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),and the like can be given. Further, as a light-emitting substance forred light emission,N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD),7,13-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD), and the like can be given.

Further, the third layer 113 may have a structure in which the abovesubstance having a high light-emitting property is dispersed in anothersubstance. Note that in the case of dispersing, the concentration of thesubstance to be dispersed is preferably set 20% or less of the total inmass ratio. Further, as a substance in which the substance having alight-emitting property is dispersed, a known substance can be used. Itis preferable to use a substance having a lowest unoccupied molecularorbital level (LUMO level) deeper (the absolute value is larger) thanthat of the substance having a light-emitting property and having ahighest occupied molecular orbital level (HOMO level) shallower (theabsolute value is smaller) than that of the substance having alight-emitting property.

Specifically, any of the following metal complexes can be used:tris(8-quinolinolato)aluminum(III) (abbreviation: Alq);tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃);bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂);bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq); bis(8-quinolinolato)zinc(II) (abbreviation: Znq);bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO);bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); andthe like.

In addition, any of the following heterocyclic compounds can be used:2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD); 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7);3-(biphenyl-4-yl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ);2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI); bathophenanthroline (abbreviation: BPhen);bathocuproine (BCP); and the like.

Besides, any of the following condensed aromatic compounds can also beused: 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-Carbazole (abbreviation:CzPA); 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-Carbazole(abbreviation: DPCzPA); 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA); 9,10-di(2-naphthyl)anthracene (abbreviation: DNA);2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA);9,9′-bianthryl (abbreviation: BANT);9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS);9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2);3,3′,3″-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3); and thelike.

As the substance in which the substance having a light-emitting propertyis dispersed, a plurality of kinds of substances can be used. Forexample, in order to suppress crystallization, a substance forsuppressing crystallization of rubrene or the like may be further added.In addition, NPB, Alq, or the like may be further added in order toefficiently transfer energy to the substance having a light-emittingproperty. Thus, with the structure in which the substance having a highlight-emitting property is dispersed in another substance,crystallization of the third layer 113 can be suppressed. Further,concentration quenching which results from the high concentration of thesubstance having a high light-emitting property can be suppressed.

Further, in particular, among the above substances, a substance havingan electron-transporting property is preferably used so that thesubstance having a light-emitting property is dispersed therein to formthe third layer 113. Specifically, it is also possible to use any of theabove metal complexes and heterocyclic compounds; CzPA, DNA, and t-BuDNAamong the above condensed aromatic compounds; and further macromolecularcompounds which will be given later as a substance that can be used forthe fourth layer 114.

Alternatively, for the third layer 113, the following macromolecularcompound can be used.

As a light-emitting substance for blue light emission,poly(9,9-dioctylfluorene-2,7-diyl) (abbreviation: POF),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,5-dimethoxybenzen-1,4-diyl)](abbreviation: PF-DMOP),poly{(9,9-dioctylfluorene-2,7-diyl)-co-[N,N′-di-(p-butylphenyl)-1,4-diaminobenzene]}(abbreviation: TAB-PFH), and the like can be given.

As a light-emitting substance for green light emission,poly(p-phenylenvinylene) (abbreviation: PPV),poly[(9,9-dihexylfluorene-2,7-diyl)-alt-co-(benzo[2,1,3]thiadiazol-4,7-diyl)](abbreviation: PFBT),poly[(9,9-dioctyl-2,7-divinylenfluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene)],and the like can be given.

As light-emitting substances for orange to red light emission,poly[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylenevinylene] (abbreviation:MEH-PPV), poly(3-butylthiophene-2,5-diyl) (abbreviation: R4-PAT),poly{[9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenylene]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]},poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-bis(1-cyanovinylenephenylene)]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]}(abbreviation: CN-PPV-DPD), and the like can be given.

The fourth layer 114 is an electron-transporting layer containing asubstance having a high electron-transporting property. For the fourthlayer 114, for example, as a low molecular organic compound, a metalcomplex such as Alq, Almq₃, BeBq₂, BAlq, Znq, ZnPBO, or ZnBTZ, or thelike can be used. Alternatively, instead of the metal complex, aheterocyclic compound such as PBD, OXD-7, TAZ, TPBI, BPhen, or BCP canbe used. The substances described here are mainly substances having anelectron mobility of 10⁻⁶ cm²/Vs or more. Note that other than the abovesubstances may be used for the electron-transporting layer as long asthe substance has a higher electron-transporting property than ahole-transporting property. Further, the electron-transporting layer isnot limited to a single layer but may also be a stack layer of two ormore layers formed of the above substances.

Alternatively, for the fourth layer 114, a macromolecular compound canbe used. For example,poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation: PF-Py),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation: PF-BPy), or the like can be used.

Further, the fifth layer 115 is an electron-injecting layer containing asubstance having a high electron-injecting property. For the fifth layer115, an alkali metal, an alkaline earth metal, or a compound thereofsuch as lithium fluoride (LiF), cesium fluoride (CsF), or calciumfluoride (CaF₂) can be used. Alternatively, a layer formed of asubstance having an electron-transporting property which contains analkali metal, an alkaline earth metal, or a compound thereof,specifically, a layer formed of Alq which contains magnesium (Mg), orthe like may be used. Note that in this case, electrons can be moreefficiently injected from a second electrode 104.

For the second electrode 104, a metal, an alloy, an electricallyconductive compound, a mixture thereof, or the like having a low workfunction (specifically, a work function of 3.8 eV or less) can be used.As a specific example of such a cathode material, an element belongingto Group 1 or 2 of the periodic table, that is, an alkali metal such aslithium (Li) or cesium (Cs), an alkaline earth metal such as magnesium(Mg), calcium (Ca), or strontium (Sr), an alloy containing any of thesemetals (such as an MgAg alloy or an AlLi alloy), a rare-earth metal suchas europium (Eu) or ytterbium (Yb), an alloy containing such rare-earthmetals, and the like can be given.

Note that in the case where the second electrode 104 is formed using analkali metal, an alkaline-earth metal, or an alloy thereof, a vacuumevaporation method or a sputtering method can be employed. Note that inthe case of using a silver paste or the like, a coating method, anink-jet method, or the like can be used.

Note that by providing the fifth layer 115, the second electrode 104 canbe formed using any of a variety of conductive materials such as Al, Ag,ITO, and indium tin oxide containing silicon or silicon oxide regardlessof their work functions. These conductive materials can be formed by asputtering method, an inkjet method, a spin coating method, or the like.

Further, as a formation method of the EL layer 103 in which the firstlayer (hole-injecting layer) 111, the second layer (hole-transportinglayer) 112, the third layer (light-emitting layer) 113, the fourth layer(electron-transporting layer) 114, and the fifth layer(electron-injecting layer) 115 are sequentially stacked, any of avariety of methods can be employed regardless of whether the method is adry process or a wet process. For example, a vacuum evaporation method,an ink-jet method, a spin coating method, or the like can be used. Notethat a different formation method may be employed for each layer.

The second electrode 104 can also be formed by a wet process such as asol-gel method using a paste of a metal material in addition to a dryprocess such as a sputtering method or a vacuum evaporation method.

In the light-emitting element of the present invention described above,current flows due to a potential difference generated between the firstelectrode 102 and the second electrode 104 and holes and electronsrecombine in the EL layer 103, whereby light is emitted. Then, thislight emission is extracted outside through one of or both the firstelectrode 102 and the second electrode 104. Therefore, one of or boththe first electrode 102 and the second electrode 104 are an electrodehaving a light-transmitting property.

Note that when only the first electrode 102 is an electrode having alight-transmitting property, light emitted from the EL layer 103 isextracted from the substrate 101 side through the first electrode 102,as shown in FIG. 2A. Alternatively, when only the second electrode 104is an electrode having a light-transmitting property, light emitted fromthe EL layer 103 is extracted from the opposite side to the substrate101 side through the second electrode 104, as shown in FIG. 2B. Furtheralternatively, when the first electrode 102 and the second electrode 104are both electrodes having a light-transmitting property, light emittedfrom the EL layer 103 is extracted to both the substrate 101 side andthe opposite side to the substrate 101 side, through the first electrode102 and the second electrode 104, as shown in FIG. 2C.

The structure of the layers provided between the first electrode 102 andthe second electrode 104 is not limited to the above. Structures otherthan the above may be employed as long as at least the second layer 112which is a hole-transporting layer and the third layer 113 which is alight-emitting layer are included.

Alternatively, as shown in FIG. 1B, a structure may be employed in whichthe second electrode 104 which functions as a cathode, the EL layer 103,and the first electrode 102 which functions as an anode are sequentiallystacked over the substrate 101. Note that the EL layer 103 in this casehas a structure in which the fifth layer 115, the fourth layer 114, thethird layer 113, the second layer 112, the first layer 111, and thefirst electrode 102 are sequentially stacked over the second electrode104.

Note that by using the light-emitting element of the present invention,a passive matrix light-emitting device or an active matrixlight-emitting device in which drive of the light-emitting element iscontrolled by a thin film transistor (TFT) can be manufactured.

Note that there is no particular limitation on the structure of the TFTin the case of manufacturing an active matrix light-emitting device. Forexample, a staggered TFT or an inverted staggered TFT can be used asappropriate. Further, a driver circuit formed over a TFT substrate maybe formed of both an n-type TFT and a p-type TFT or only either ann-type TFT or a p-type TFT. Furthermore, there is no particularlimitation on the crystallinity of a semiconductor film used for theTFT. Either an amorphous semiconductor film or a crystallinesemiconductor film may be used for the TFT.

Since the second layer (hole-transporting layer) 112 is formed using thecarbazole derivative of the present invention in the light-emittingelement which is shown in Embodiment Mode 2, not only improvement inelement efficiency but also suppress of increase in drive voltage can berealized.

Note that Embodiment Mode 2 can be combined with any of the structuresdescribed in Embodiment Mode 1 as appropriate.

Embodiment Mode 3

In Embodiment Mode 3, a light-emitting element having a plurality of ELlayers any of the light-emitting elements described in Embodiment Mode 2(hereinafter referred to as a stacked-type light-emitting element) willbe described with reference to FIG. 3. This light-emitting element is astacked-type light-emitting element that has a plurality of EL layers (afirst EL layer 303 and a second EL layer 304) between a first electrode301 and a second electrode 302. Note that although a structure of two ELlayers is described in Embodiment Mode 3, a structure of three or moreEL layers may also be employed.

In Embodiment Mode 3, the first electrode 301 functions as an anode, andthe second electrode 302 functions as a cathode. Note that for the firstelectrode 301 and the second electrode 302, structures similar to thosedescribed in Embodiment Mode 1 can be employed. Further, for theplurality of EL layers (the first EL layer 303 and the second EL layer304), structures similar to those described in Embodiment Mode 2 can beemployed. Note that structures of the first EL layer 303 and the secondEL layer 304 may be the same or different from each other and can besimilar to those described in Embodiment Mode 2.

Further, a charge generation layer 305 is provided between the pluralityof EL layers (the first EL layer 303 and the second EL layer 304). Thecharge generation layer 305 has a function of injecting electrons intoone of the EL layers and injecting holes into the other of the EL layerswhen voltage is applied to the first electrode 301 and the secondelectrode 302. In Embodiment Mode 3, when voltage is applied so that thepotential of the first electrode 301 is higher than that of the secondelectrode 302, the charge generation layer 305 injects electrons intothe first EL layer 303 and injects holes into the second EL layer 304.

Note that the charge generation layer 305 preferably has alight-transmitting property in terms of light extraction efficiency.Further, the charge generation layer 305 functions even when it haslower conductivity than the first electrode 301 or the second electrode302.

The charge generation layer 305 may have either a structure in which asubstance having an acceptor property is added to a substance having ahigh hole-transporting property or a structure in which a substancehaving a donor property is added to a substance having a highelectron-transporting property. Alternatively, both of these structuresmay be stacked.

In the case of employing the structure in which a substance having anacceptor property is added to a substance having a highhole-transporting property, as the substance having a highhole-transporting property, for example, an aromatic amine compound suchas 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB orα-NPD), N N′-bis(3-methylphenyl)-NN′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (abbreviation: TPD),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA), or4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]-1,1′-biphenyl(abbreviation: BSPB) can be used. The substances described here aremainly substances having a hole mobility of greater than or equal to10⁻⁶ cm²/Vs. Note that substances other than the substances describedabove may also be used as long as the hole-transporting propertiesthereof are higher than the electron-transporting properties thereof.

In addition, as the substance having an acceptor property,7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ), chloranil, and the like can be given. In addition, atransition metal oxide can be given. Moreover, oxides of metalsbelonging to Groups 4 to 8 of the periodic table can be given.Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromiumoxide, molybdenum oxide, tungsten oxide, manganese oxide, and rheniumoxide are preferable because of a high electron-accepting property.Among these, molybdenum oxide is especially preferable because it isstable in the air and its hygroscopic property is low so that it can beeasily treated.

On the other hand, in the case of employing the structure in which asubstance having a donor property is added to a substance having a highelectron-transporting property, as the substance having a highelectron-transporting property, for example, a metal complex having aquinoline skeleton or a benzoquinoline skeleton, such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),or bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), can be used. Besides, a metal complex having anoxazole-based ligand or a thiazole-based ligand, such asbis[2-(2′-hydroxyphenyl)benzoxazolato]zinc(II) (abbreviation: Zn(BOX)₂)or bis[2-(2′-hydroxyphenyl)benzothiazolato]zinc(II) (abbreviation:Zn(BTZ)₂), can also be used. Further, other than the metal complexes,any of the following can also be used:2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD); 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7);3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ); bathophenanthroline (abbreviation: BPhen);bathocuproine (BCP); or the like. The substances described here aremainly substances having an electron mobility of 10⁻⁶ cm²/Vs or more.Note that other than the above substances may be used as long as thesubstance has a higher electron-transporting property than ahole-transporting property.

Further, for the substance having a donor property, an alkali metal, analkaline-earth metal, a rare-earth metal, a metal belonging to Group 13of the periodic table, or an oxide or carbonate thereof can be used.Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca),ytterbium (Yb), indium (In), lithium oxide, cesium carbonate, or thelike is preferably used. Alternatively, an organic compound such astetrathianaphthacene may be used as the substance having a donorproperty.

Note that by forming the charge generation layer 305 using any of theabove materials, increase in drive voltage in the case where the ELlayers are stacked can be suppressed.

Although the light-emitting element having two EL layers is described inEmbodiment Mode 3, the present invention can be similarly applied to alight-emitting element in which three or more EL layers are stacked. Byarranging a plurality of EL layers to be partitioned from each otherwith a charge generation layer between a pair of electrodes, like thelight-emitting element according to Embodiment Mode 3, a long lifetimeelement in a high luminance region can be realized while current densityis kept low. In a case where the light-emitting element is applied tolighting as an application example, voltage drop due to resistance of anelectrode material can be reduced. Accordingly, light can be uniformlyemitted in a large area. Moreover, a light-emitting device whichconsumes low power and is driven at low voltage can be achieved.

Further, when the EL layers have different emission colors, a desiredemission color can be obtained from the whole light-emitting element.For example, in the light-emitting element having two EL layers, when anemission color of the first EL layer and an emission color of the secondEL layer are made to be complementary colors, a light-emitting elementemitting white light as a whole light-emitting element can also beobtained. Note that “complementary color” means a relation betweencolors which becomes an achromatic color when they are mixed. That is,white light emission can be obtained by mixture of lights obtained fromsubstances emitting the lights of complementary colors.

Also in a light-emitting element having three EL layers, for example,white light as a whole light-emitting element can be similarly obtainedwhen an emission color of a first EL layer is red, an emission color ofa second EL layer is green, and an emission color of a third EL layer isblue.

Note that Embodiment Mode 3 can be combined with any of the structuresdescribed in Embodiment Modes 1 and 2 as appropriate.

Embodiment Mode 4

In Embodiment Mode 4, a light-emitting device having the light-emittingelement of the present invention in a pixel portion will be describedwith reference to FIGS. 4A and 4B. FIG. 4A is a top view of thelight-emitting device, and FIG. 4B is a cross sectional view taken alongA-A′ and B-B′ in FIG. 4A.

In FIG. 4A, reference numerals 401, 402, and 403 which are shown by adotted line denote a driver circuit portion (a source driver circuit), apixel portion, and a driver circuit portion (a gate driver circuit),respectively. Reference numerals 404 and 405 denote a sealing substrateand a sealant, respectively, and an inner side region enclosed by thesealant 405 is a space 407.

A lead wiring 408 is a wiring to transmit a signal to be inputted to thesource driver circuit portion 401 and the gate driver circuit 403, andreceives a video signal, a clock signal, a start signal, a reset signal,and the like from a flexible printed circuit (FPC) 409 which serves asan external input terminal. Although only the FPC is shown here, thisFPC may be provided with a printed wiring board (PWB). Further, thelight-emitting device in this specification includes not only alight-emitting device itself but also a light-emitting device attachedwith an FPC or a PWB.

Next, a cross-sectional structure of the light-emitting device will bedescribed with reference to FIG. 4B. The driver circuit portion and thepixel portion are formed over an element substrate 410. Here, one pixelin the pixel portion 402 and the source driver circuit 401 which is thedriver circuit portion are shown. As the source driver circuit 401, aCMOS circuit which is obtained by combining an n-channel TFT 423 and ap-channel TFT 424 is formed. The driver circuit may be formed by variousCMOS circuits, PMOS circuits, or NMOS circuits. In Embodiment Mode 4,although a driver-integrated type structure in which a driver circuit isformed over a substrate is described, a driver circuit is notnecessarily formed over a substrate but can be formed externally from asubstrate.

The pixel portion 402 is formed of a plurality of pixels having aswitching TFT 411, a current control TFT 412, and a first electrode 413electrically connected to a drain of the current control TFT 412. Aninsulator 414 is formed to cover an end portion of the first electrode413.

The insulator 414 is preferably formed so as to have a curved surfacewith curvature at an upper end portion or a lower end portion thereof inorder to obtain favorable coverage. For example, by using positive-typephotosensitive acrylic as a material of the insulator 414, the insulator414 can be formed to have a curved surface with a curvature radius (0.2μm to 3 μm) only at the upper end portion. Further, either anegative-type photosensitive material which becomes insoluble in anetchant by light irradiation or a positive-type photosensitive materialwhich becomes soluble in an etchant by light irradiation can be used asthe insulator 414.

An EL layer 416 and a second electrode 417 are formed over the firstelectrode 413. Here, the first electrode 413 can be formed using any ofa variety of materials such as metals, alloys, and electricallyconductive compounds, or a mixture thereof. Note that as specificmaterials, the materials which are shown in Embodiment Mode 2 as amaterial that can be used for the first electrode can be used.

In addition, the EL layer 416 is formed by any of a variety of methodssuch as an evaporation method using an evaporation mask, an ink-jetmethod, or a spin coating method. The EL layer 416 has the structuredescribed in Embodiment Mode 2. As another material included in the ELlayer 416, a low molecular compound or a macromolecular compound(including an oligomer or a dendrimer) may be used. As the material forthe EL layer, not only an organic compound but also an inorganiccompound may also be used.

As a material for the second electrode 417, any of a variety of metals,alloys, and electrically conductive compounds, or a mixture thereof canbe used. In the case where the second electrode 417 is used as acathode, a metal, an alloy, an electrically conductive compound, amixture thereof, or the like with a low work function (a work functionof 3.8 eV or less) is preferably used, among others. For example, anelement belonging to Group 1 or 2 of the periodic table, that is, analkali metal such as lithium (Li) or cesium (Cs), an alkaline-earthmetal such as magnesium (Mg), calcium (Ca), or strontium (Sr), or analloy containing any of these metals (such as a MgAg alloy or an AlLialloy); and the like can be given.

Note that in the case where light generated in the EL layer 416 istransmitted through the second electrode 417, for the second electrode417, a stack of a metal thin film with a reduced thickness and atransparent conductive film (indium tin oxide (ITO), indium tin oxidecontaining silicon or silicon oxide, indium zinc oxide (IZO), or indiumoxide containing tungsten oxide and zinc oxide, or the like) can also beused.

By attaching the sealing substrate 404 and the element substrate 410with the sealant 405, there is a structure where a light-emittingelement 418 is provided in the space 407 surrounded by the elementsubstrate 410, the sealing substrate 404, and the sealant 405. Note thatthe space 407 is filled with a filler such as an inert gas (e.g.,nitrogen, argon, or the like) or the sealant 405.

It is preferable to use an epoxy-based resin as the sealant 405. Inaddition, it is preferable that the material do not transmit moistureand oxygen as much as possible. As a material for the sealing substrate404, a plastic substrate formed of FRP (Fiberglass-Reinforced Plastics),PVF (polyvinyl fluoride), polyester, acrylic, or the like can be used aswell as a glass substrate or a quartz substrate.

As described above, an active matrix light-emitting device having thelight-emitting element of the present invention can be obtained.

Further, the light-emitting element of the present invention can also beused for a passive matrix light-emitting device in addition to the aboveactive matrix light-emitting device. FIGS. 5A and 5B respectively show aperspective view and a cross-sectional view of a passive matrixlight-emitting device using the light-emitting element of the presentinvention. Note that FIG. 5A is a perspective view of the light-emittingdevice, and FIG. 5B is a cross-sectional view of FIG. 5A taken alongline X-Y.

In FIGS. 5A and 5B, an EL layer 504 is provided between a firstelectrode 502 and a second electrode 503 over a substrate 501. An edgeportion of the first electrode 502 is covered with an insulating layer505. Then, a partition layer 506 is provided over the insulating layer505. Sidewalls of the partition layer 506 have a slant such that adistance between one sidewall and the other sidewall becomes narrower asthe sidewalls gets closer to a surface of the substrate. In other words,a cross section of the partition layer 506 in the direction of a shortside is trapezoidal, and a lower base (a side facing a similar directionas a plane direction of the insulating layer 505 and in contact with theinsulating layer 505) is shorter than an upper base (a side facing asimilar direction as the plane direction of the insulating layer 505 andnot in contact with the insulating layer 505). By providing thepartition layer 506 in such a manner, a defect of the light-emittingelement due to static electricity or the like can be prevented.

Through the above process, the passive matrix light-emitting deviceusing the light-emitting element of the present invention can beobtained.

Note that any of the light-emitting devices described in Embodiment Mode4 (the active matrix light-emitting device and the passive matrixlight-emitting device) are formed using the light-emitting element ofthe present invention, which has high luminous efficiency, andaccordingly a light-emitting device having reduced power consumption canbe obtained.

Note that Embodiment Mode 4 can be combined with any of the structuresdescribed in Embodiment Modes 1 to 3 as appropriate.

Embodiment Mode 5

In Embodiment Mode 5, an electronic device including, as part thereof,the light-emitting device of the present invention which is shown inEmbodiment Mode 4 will be described. Examples of the electronic deviceinclude cameras such as video cameras or digital cameras, goggle typedisplays, navigation systems, audio reproducing devices (e.g., car audiosystems and audio components), computers, game machines, portableinformation terminals (e.g., mobile computers, cellular phones, portablegame machines, and electronic books), image reproducing devices in whicha recording medium is provided (specifically, devices that are capableof reproducing recording media such as digital versatile discs (DVDs)and equipped with a display unit that can display images), and the like.Specific examples of these electronic devices are shown in FIGS. 6A to6D.

FIG. 6A shows a television set according to the present invention, whichincludes a housing 611, a supporting base 612, a display portion 613,speaker portions 614, video input terminals 615, and the like. In thistelevision set, the light-emitting device of the present invention canbe applied to the display portion 613. Since the light-emitting deviceof the present invention has a feature of high luminous efficiency, atelevision set having reduced power consumption can be obtained byapplying the light-emitting device of the present invention.

FIG. 6B shows a computer according to the present invention, whichincludes a main body 621, a housing 622, a display portion 623, akeyboard 624, an external connection port 625, a pointing device 626,and the like. In this computer, the light-emitting device of the presentinvention can be applied to the display portion 623. Since thelight-emitting device of the present invention has a feature of highluminous efficiency, a computer having reduced power consumption can beobtained by applying the light-emitting device of the present invention.

FIG. 6C shows a cellular phone according to the present invention, whichincludes a main body 631, a housing 632, a display portion 633, an audioinput portion 634, an audio output portion 635, operation keys 636, anexternal connection port 637, an antenna 638, and the like. In thiscellular phone, the light-emitting device of the present invention canbe applied to the display portion 633. Since the light-emitting deviceof the present invention has a feature of high luminous efficiency, acellular phone having reduced power consumption can be obtained byapplying the light-emitting device of the present invention.

FIG. 6D shows a camera according to the present invention, whichincludes a main body 641, a display portion 642, a housing 643, anexternal connection port 644, a remote control receiving portion 645, animage receiving portion 646, a battery 647, an audio input portion 648,operation keys 649, an eyepiece portion 650, and the like. In thiscamera, the light-emitting device of the present invention can beapplied to the display portion 642. Since the light-emitting device ofthe present invention has a feature of high luminous efficiency, acamera having reduced power consumption can be obtained by applying thelight-emitting device of the present invention.

As described above, the applicable range of the light-emitting device ofthe present invention is so wide that the light-emitting device can beapplied to electronic devices in a variety of fields.

The light-emitting device of the present invention can also be used as alighting device. FIG. 7 is an example of a liquid crystal display devicein which the light-emitting device of the present invention is used as abacklight. The liquid crystal display device shown in FIG. 7 includes ahousing 701, a liquid crystal layer 702, a backlight 703, and a housing704. The liquid crystal layer 702 is connected to a driver IC 705. Thelight-emitting device of the present invention is used for the backlight703, and current is supplied through a terminal 706.

With the use of the light-emitting device of the present invention as abacklight of a liquid crystal display device as described above, abacklight which consumes low power can be obtained. Further, since thelight-emitting device of the present invention is a plane emittinglighting device and the area thereof can be enlarged, the backlight canalso have a large area. Therefore, a larger-area liquid crystal displaydevice which consumes low power can be obtained.

FIG. 8 shows an example of using the light-emitting device, to which thepresent invention is applied, as a table lamp, which is a lightingdevice. A table lamp shown in FIG. 8 has a housing 801 and a lightsource 802, and the light-emitting device of the present invention isused as the light source 802. The light-emitting device of the presentinvention has the light-emitting element having high luminous efficiencyand therefore can be used as a desk lamp which consumes low power.

FIG. 9 shows an example of using the light-emitting device, to which thepresent invention is applied, as an indoor lighting device 901. Sincethe area of the light-emitting device of the present invention can alsobe enlarged, the light-emitting device of the present invention can beused as a lighting device having a large area. In addition, thelight-emitting device of the present invention has the light-emittingelement having high luminous efficiency and therefore can be used as alighting device which consumes low power. When a television set 902according to the present invention as described in FIG. 6A is placed ina room in which the light-emitting device, to which the presentinvention is applied, is used as the indoor lighting device 901, publicbroadcasting and movies can be watched.

Note that Embodiment Mode 5 can be combined with any of the structuresdescribed in Embodiment Modes 1 to 4 as appropriate.

Embodiment 1

In Embodiment 1, a synthetic method of a carbazole derivative of thepresent invention, 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation; PCBA1BP) represented by a structural formula (5), will bespecifically described.

Step 1: Synthesis of 4-bromo-diphenylamine

A synthetic scheme of 4-bromo-diphenylamine in Step 1 is shown in thefollowing (D-1).

After 51 g (0.3 mol) of diphenylamine was dissolved in 700 mL of ethylacetate in a 1-L conical flask, 54 g (0.3 mol) of N-bromo succinimide(abbreviation: NBS) was added to this solution. About 300 hours later,this mixture solution was washed with water and then magnesium sulfatewas added thereto to remove moisture. This mixture solution wasfiltrated, and the filtrate was concentrated and collected. Accordingly,70 g of a dark brown oil-like object was obtained at a yield of 94%.

Step 2-1: Synthesis of 3-bromo-9-phenyl-9H-carbazole

A synthetic scheme of 3-bromo-9-phenyl-9H-carbazole in Step 2-1 is shownin the following (D-2-1).

In a 1000 mL conical flask, 24 g (100 mmol) of 9-phenyl-9H-carbazole, 18g (100 mmol) of N-bromo succinimide, 450 mL of toluene, and 200 mL ofethyl acetate were added, and the mixture was stirred at roomtemperature for 45 hours. This suspension was washed with water and thenmagnesium sulfate was added thereto to remove moisture. This suspensionwas filtrated, and the obtained filtrate was concentrated and dried.Accordingly, 32 g of a caramel-like object,3-bromo-9-phenyl-9H-carbazole, was obtained at a yield of 99%.

Step 2-2: Synthesis of 9-phenyl-9H-carbazol-3-boronic acid

A synthetic scheme of 9-phenyl-9H-carbazol-3-boronic acid in Step 2-2 isshown in the following (D-2-2).

In a 500-mL conical flask, 29 g (90 mmol) of3-bromo-9-phenyl-9H-carbazole and 200 mL of tetrahydrofuran (THF) werestirred at −78° C. to be a solution. After that, 110 mL (69 mmol) ofn-butyllithium (a 1.57 mol/L hexane solution) was dropped into thissolution and was stirred at the same temperature for 2 hours. Further,13 mL (140 mmol) of trimethyl borate was added to this solution, and thesolution was stirred at room temperature for 24 hours.

After completion of the reaction, 200 mL of hydrochloric acid (1.0mol/L) was added to the reaction mixture, and then the mixture wasstirred at room temperature for 1 hour. This mixture was washed with asodium hydroxide aqueous solution and water in this order, and magnesiumsulfate was added to remove moisture. This suspension was filtrated, theobtained filtrate was concentrated, and chloroform and hexane were addedthereto. The mixture was irradiated with supersonic. After that,recrystallization was performed. Accordingly, 21 g of an objective whitepowder, 9-phenyl-9H-carbazol-3-boronic acid, was obtained at a yield of80%.

Step 3: Synthesis of 4-(9-phenyl-9H-carbazol-3-yl)diphenylamine(Abbreviation: PCBA)

A synthetic scheme of 4-(9-phenyl-9H-carbazol-3-yl)diphenylamine(abbreviation: PCBA) in Step 3 is shown in the following (D-3).

In a 500-mL three-neck flask, 6.5 g (26 mmol) of 4-bromodiphenylamine,7.5 g (26 mmol) of 9-phenyl-9H-carbazol-3-boronic acid, and 400 mg (1.3mmol) of tri(o-tolyl)phosphine were put, and the atmosphere in the flaskwas substituted by nitrogen. Then, 100 mL of toluene, 50 mL of ethanol,and 14 mL of potassium carbonate solution (0.2 mol/L) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, 67 mg (30 mmol) of palladium(II) acetatewas added thereto.

This mixture was refluxed at 100° C. for 10 hours. After the reflux, theaqueous layer of this mixture was extracted with toluene. Then, theextracted solution was combined with an organic layer, followed bywashing with a saturated saline solution. After the moisture of theorganic layer was removed by magnesium sulfate, this mixture wasnaturally filtrated, and the obtained filtrate was concentrated toobtain an oily light-brown substance. This oily substance was purifiedby silica gel column chromatography (developing solvent, hexane:toluene=4:6). A white solid which was obtained after the purificationwas recrystallized with dichloromethane/hexane, and 4.9 g of anobjective white solid was obtained at a yield of 45%.

Step 4: Synthesis of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (Abbreviation:PCBA1BP)

A synthetic scheme of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP) in Step 4 is shown in the following (D-4).

In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of4-(9-phenyl-9H-carbazol-3-yl)diphenylamine, 1.1 g (4.9 mmol) of4-bromobiphenyl, and 2.0 g (20 mmol) of sodium tert-butoxide were put,and the atmosphere in the flask was substituted by nitrogen. Then, 50 mLof toluene and 0.30 mL of tri(tert-butyl)phosphine (10 wt % hexanesolution) were added to this mixture.

This mixture was deaerated while being stirred under low pressure. Afterthe deaeration, 0.10 g of bis(dibenzylideneacetone)palladium(0) wasadded thereto. Next, this mixture was stirred at 80° C. for 5 hours tobe reacted. After the reaction, toluene was added to the reactionmixture, and suction filtration was performed on this suspension throughCelite, alumina, and then Florisil to obtain filtrate. The obtainedfiltrate was washed with a saturated sodium carbonate solution and asaturated saline solution in this order. Magnesium sulfate was added tothe organic layer, and the organic layer was dried. After the drying,suction filtration was performed on this mixture to remove the magnesiumsulfate; thus, the filtrate was obtained.

The obtained filtrate was concentrated and purified by silica gel columnchromatography. The silica gel column chromatography was performed by,first, using a mixture solvent of toluene:hexane=1:9 as a developingsolvent, and then using a mixture solvent of toluene:hexane=3:7 asanother developing solvent. A solid which was obtained by concentratingthe obtained fraction was recrystallized with a mixture solvent ofchloroform and hexane to obtain 2.3 g of a white powder-like solid at ayield of 84%.

Sublimation purification of 1.2 g of the obtained white solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa, with a flow rate ofargon at 3 mL/min, at 280° C. for 20 hours. Accordingly, 1.1 g of thewhite solid was obtained at a yield of 89%.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 10A and 10B. Itwas found from the measurement result that the carbazole derivative ofthe present invention,4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP) represented by the above structural formula (5), was obtained.

¹H NMR (DMSO-d, 300 MHz): δ (ppm)=7.05-7.20 (m, 7H), 7.28-7.78 (m, 21H),8.34 (d, J=7.8 Hz, 1H), 8.57 (s, 1H).

In addition, an absorption spectrum of a toluene solution of PCBA1BP(abbreviation) is shown in FIG. 11A. In addition, an absorption spectrumof a thin film of PCBA1BP (abbreviation) is shown in FIG. 11B. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for the measurement. The spectrum of the solutionwas measured in a quartz cell. The sample of the thin film wasfabricated by vapor evaporation of PCBA1BP (abbreviation) over a quartzsubstrate. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured sample is shown in FIG.11A, and the absorption spectrum of the thin film which was obtained bysubtracting the quartz substrate from the measured sample is shown inFIG. 11B.

In FIGS. 11A and 11B, the horizontal axis indicates the wavelength (nm)and the vertical axis indicates the absorption intensity (arbitraryunit). In the case of the toluene solution, an absorption peak wasobserved at around 335 nm, and in the case of the thin film, anabsorption peak was observed at around 341 nm. In addition, an emissionspectrum of the toluene solution (excitation wavelength: 346 nm) ofPCBA1BP (abbreviation) is shown in FIG. 11A. In addition, an emissionspectrum of the thin film (excitation wavelength: 386 nm) of PCBA1BP(abbreviation) is shown in FIG. 11B. In FIGS. 11A and 11B, thehorizontal axis indicates the wavelength (nm) and the vertical axisindicates the light emission intensity (arbitrary unit). The maximumemission wavelength was 391 nm (excitation wavelength: 346 nm) in thecase of the toluene solution and 416 nm (excitation wavelength: 386 nm)in the case of the thin film.

An oxidation-reduction reaction characteristic of PCBA1BP (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Anelectrochemical analyzer (ALS model 600A or 600C, manufactured by BASInc.) was used for the measurement.

As for a solution used in the CV measurement, dehydrateddimethylformamide (DMF) (manufactured by Aldrich, 99.8%, catalog number:22705-6) was used as a solvent, and tetra-n-butylammonium perchlorate(n-Bu₄NClO₄, product of Tokyo Chemical Industry Co., Ltd., catalog No.T0836), which was a supporting electrolyte, was dissolved in the solventsuch that the concentration thereof was 100 mmol/L. Further, the objectto be measured was also dissolved in the solvent such that theconcentration thereof was 2 mmol/L. A platinum electrode (PTE platinumelectrode, manufactured by BAS Inc.) was used as a working electrode,another platinum electrode (Pt counter electrode for VC-3 (5 cm),manufactured by BAS Inc.) was used as an auxiliary electrode, and anAg/Ag⁺ electrode (RE7 reference electrode for nonaqueous solvent,manufactured by BAS Inc.) was used as a reference electrode. Note thatthe measurement was performed at room temperature (20° C. to 25° C.). Inaddition, the scan speed at the CV measurement was 0.1 V/sec.

(Calculation of the Potential Energy of the Reference Electrode withRespect to the Vacuum Level)

First, potential energy (eV) of the reference electrode (Ag/Ag⁺electrode) used in Embodiment 1 with respect to the vacuum level wascalculated. That is, the Fermi level of the Ag/Ag⁺ electrode wascalculated. It is known that the oxidation-reduction potential offerrocene in methanol is +0.610 V [vs. SHE] with respect to a standardhydrogen electrode (Reference: Christian R. Goldsmith et al., J. Am.Chem. Soc., Vol. 124, No. 1, pp. 83-96, 2002). On the other hand, theoxidation-reduction potential of ferrocene in methanol measured by usingthe reference electrode used in Embodiment 1 was found to be +0.11 V[vs. Ag/Ag⁺]. Therefore, it was found that the potential energy of thereference electrode used in Embodiment 1 was less than that of thestandard hydrogen electrode by 0.50 [eV].

Here, it is also known that the potential energy of the standardhydrogen electrode with respect to the vacuum level is (−4.44 eV(Reference: Toshihiro Ohnishi and Tamami Koyama, Macromolecular ELmaterial, Kyoritsu Shuppan, pp. 64-67). As described above, thepotential energy of the reference electrode used in Embodiment 1 withrespect to the vacuum level was calculated to be −4.44-0.50=−4.94 [eV].

FIG. 41 shows the CV measurement result on the oxidation reactioncharacteristics. Note that the measurement of the oxidation reactioncharacteristics was performed by the steps of scanning the potential ofthe working electrode with respect to the reference electrode in rangesof (1) 0.07 V to 1.00 V, and then (2) 1.00 V to 0.07 V

First, the calculation of the HOMO level of PCBA1BP (abbreviation) by CVmeasurement is described in detail. As shown in FIG. 41, an oxidizationpeak potential E_(pa) was 0.536 V. In addition, a reduction peakpotential E_(pc) was 0.446 V. Therefore, a half-wave potential (anintermediate potential between E_(pc) and E_(pa)) can be calculated tobe 0.49 V. This shows that PCBA1BP (abbreviation) can be oxidized by anelectrical energy of 0.49 V [vs. Ag/Ag⁺], and this energy corresponds tothe HOMO level. Here, the potential energy of the reference electrodeused in Embodiment 1 with respect to the vacuum level is −4.94 [eV] asdescribed above. Therefore, the HOMO level of PCBA1BP (abbreviation) wasfound to be −4.94-0.49=−5.43 [eV]. In addition, the oxidation peak tooka similar value even after the 100 cycles. Accordingly, it was foundthat repetition of the oxidation reduction between an oxidation stateand a neutral state had favorable characteristics.

Embodiment 2

In Embodiment 2, a synthetic method of a carbazole derivative of thepresent invention,4,4′-diphenyl-4″-(9-phenyl-9-H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP) represented by a structural formula (6), willbe specifically described.

Step 1-1: Synthesis of 4-phenyl-diphenylamine

A synthetic scheme of 4-phenyl-diphenylamine in Step 1-1 is shown in thefollowing (E-1-1).

In a three-neck flask, 5.2 g (2.5 mmol) of tri-tert-butylphosphine (10wt % hexane solution) was added to a dehydrated xylene suspension (150mL) containing 20.0 g (85.8 mmol) of 4-bromobiphenyl, 16.0 g (172 mmol)of aniline, 0.19 g (0.86 mmol) of palladium(II) acetate, and 23.7 g (172mmol) of potassium carbonate, and a mixture thereof was refluxed under anitrogen atmosphere at 120° C. for 10 hours. After completion of thereaction, the reaction mixture was washed with water and separated intoan organic layer and an aqueous layer, and the aqueous layer wasextracted with toluene.

The above obtained toluene layer was combined with the above organiclayer, followed by washing with a saturated saline solution. Then,magnesium sulfate was added thereto to remove moisture in the organiclayer. Suction filtration was performed on this mixture to concentratethe obtained filtrate. The obtained residue was purified by silica gelcolumn chromatography (a developing was solvent: toluene). Accordingly,13.5 g of a white solid of 4-phenyl-diphenylamine, which was obtained byconcentrating the obtained solution, was obtained at a yield of 64%.

Step 1-2: Synthesis of 4,4′-diphenyltriphenylamine

A synthetic scheme of 4,4′-diphenyltriphenylamine in Step 1-2 is shownin the following (E-1-2).

In a 100-mL three-neck flask, 3.7 g (15 mmol) of 4-phenyl-diphenylamine,3.5 g (15 mmol) of 4-bromobiphenyl, 2.5 g (25 mmol) of sodiumtert-butoxide, and 10 mg (0.02 mmol) ofbis(dibenzylideneacetone)palladium(0) were put, and the atmosphere inthe flask was substituted by nitrogen. Then, 40 mL of dehydrated xylenewas added to this mixture. The mixture was deaerated while being stirredunder low pressure. After the deaeration, 0.2 mL (60 mmol) oftri(tert-butyl)phosphine (10 wt % hexane solution) was added thereto.

Next, this mixture was stirred at 120° C. for 5 hours, to be reacted.After the reaction, toluene was added to the reaction mixture, andsuction filtration was performed on this suspension through Celite,alumina, and then Florisil to obtain filtrate. The obtained filtrate waswashed with a saturated sodium carbonate solution and a saturated salinesolution in this order. Magnesium sulfate was added to the obtainedorganic layer to remove moisture. Suction filtration was performed onthis mixture through Celite, alumina, and then Florisil to concentratethe obtained filtrate. Acetone and methanol were added to the obtainedresidue, and the residue was irradiated with supersonic and thenrecrystallized to obtain 5.4 g of a white powder-like solid at a yieldof 92%.

Step 1′: Synthesis of 4,4′-diphenyltriphenylamine

In addition to Step 1-1 and Step 1-2 which are described above,4,4′-diphenyltriphenylamine can also be synthesized using a syntheticmethod shown in Step 1′. Note that a synthetic scheme of4,4′-diphenyltriphenylamine in Step 1′ is shown in the following (E-1′).

In a 200-mL three-neck flask, 1.9 g (20 mmol) of aniline, 9.3 g (40mmol) of 4-bromobiphenyl, 4.5 g (45 mmol) of sodium tert-butoxide, 0.4 g(2.0 mmol) of palladium(II) acetate, and 1.1 g (2.0 mmol) of1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF) were put, andthe atmosphere in the flask was substituted by nitrogen. Then, 70 mL ofdehydrated xylene was added to this mixture. This mixture was deaeratedwhile being stirred under low pressure, and the mixture was stirred at110° C. for 3 hours to be reacted. After the reaction, toluene was addedto the reaction mixture, and suction filtration was performed on thissuspension through Celite, alumina, and then Florisil to obtainfiltrate. The obtained filtrate was washed with a saturated sodiumcarbonate solution and a saturated saline solution in this ordelMagnesium sulfate was added to the obtained organic layer to removemoisture. Suction filtration was performed on this mixture throughCelite, alumina, and then Florisil to concentrate the obtained filtrate.Acetone and hexane were added to the obtained residue, and the residuewas irradiated with supersonic and then recrystallized to obtain 5.4 gof a white powder-like solid at a yield of 67%.

Step 2: Synthesis of 4-bromo-4′,4″-diphenyltriphenylamine

With the use of Step 1-1 and Step 1-2 which are described above, or4,4′-diphenyltriphenylamine which was synthesized using a syntheticmethod shown in Step 1′, 4-bromo-4′,4″-diphenyltriphenylamine issynthesized. Note that a synthetic scheme of4-bromo-4′,4″-diphenyltriphenylamine in Step 2 is shown in the following(E-2).

After 4.0 g (10 mmol) of 4,4′-diphenyltriphenylamine was dissolved in amixture solvent of 50 mL of toluene and 50 mL of ethyl acetate in aconical flask, N-bromo succinimide (abbreviation: NBS) was added to thissolution. After that, this mixture was stirred at room temperature for120 hours. After completion of the reaction, this mixture solution waswashed with water, and magnesium sulfate was added thereto to removemoisture. This mixture solution was filtrated and the obtained filtratewas concentrated to perform recrystallization. Accordingly, 4.5 g of anobjective white powder was obtained at a yield of 95%.

Step 3: Synthesis of4,4′-diphenyl-4″-(9-phenyl-9-H-carbazol-3-yl)triphenylamine(Abbreviation: PCBBi1BP)

A synthetic scheme of4,4′-diphenyl-4″-(9-phenyl-9-H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP) in Step 3 is shown in the following (E-3).

In a 100-mL three-neck flask, 1.5 g (3.1 mmol) of4-bromo-4′,4″-diphenyltriphenylamine, 0.9 g (3.1 mmol) of9-phenyl-9H-carbazol-3-boronic acid, 50 mg (0.023 mmol) of palladium(II)acetate, and 0.050 g (0.17 mmol) of tri(o-tolyl)phosphine were put, andthe atmosphere in the flask was substituted by nitrogen. Note that sincea synthetic method of 9-phenyl-9H-carbazol-3-boronic acid is similar tothat described in Embodiment 1, the description is to be referredthereto; thus, description here is omitted. 30 mL ofethyleneglycoldimethylether (DME) and 15 mL of potassium carbonatesolution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,this mixture was stirred at 90° C. for 5 hours to be reacted.

After the reaction, ethyl acetate was added to the reaction mixture, andthis suspension was washed with a saturated sodium hydrogen carbonatesolution and a saturated saline solution. Magnesium sulfate was added toan organic layer, and the organic layer was dried. After the drying,suction filtration was performed on this mixture to remove the magnesiumsulfate; thus, filtrate was obtained. Toluene was added to a solid whichwas obtained by concentrating the obtained filtrate and the mixture wasdissolved. Then, suction filtration was performed on this solutionthrough Celite, alumina and Florisil to obtain filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography. The silica gel column chromatography was performed by,first, using a mixture solvent of toluene:hexane=1:9 as a developingsolvent, and then using a mixture solvent of toluene:hexane=3:7 asanother developing solvent.

A solid which was obtained by concentrating the obtained fraction wasrecrystallized with a mixture solvent of dichloromethane and hexane toobtain 1.3 g of an objective white solid at a yield of 66%. Sublimationpurification of 1.1 g of the obtained white solid was performed by atrain sublimation method. The sublimation purification was performedunder a reduced pressure of 7.0 Pa, with a flow rate of argon at 4mL/min, at 305° C. for 15 hours. Accordingly, 840 mg of the white solidwas obtained at a yield of 76%.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 12A and 12B. Itwas found from the measurement result that the carbazole derivative ofthe present invention,4,4′-diphenyl-4″-(9-phenyl-9-H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP) represented by the above structural formula(6), was obtained.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.25-7.69 (m, 32H), 8.19 (d, J=7.3 Hz,1H), 8.35 (s, 1H).

In addition, an absorption spectrum of a toluene solution of PCBBi1BP(abbreviation) is shown in FIG. 13A. In addition, an absorption spectrumof a thin film of PCBBi1BP (abbreviation) is shown in FIG. 13B. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for the measurement. The spectrum of the solutionwas measured in a quartz cell. The sample of the thin film wasfabricated by vapor evaporation of PCBBi1BP (abbreviation) over a quartzsubstrate. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured sample is shown in FIG.13A, and the absorption spectrum of the thin film which was obtained bysubtracting the quartz substrate from the measured sample is shown inFIG. 13B. In FIGS. 13A and 13B, the horizontal axis indicates thewavelength (nm) and the vertical axis indicates the absorption intensity(arbitrary unit). In the case of the toluene solution, an absorptionpeak was observed at around 347 nm, and in the case of the thin film, anabsorption peak was observed at around 350 nm. In addition, an emissionspectrum of the toluene solution (excitation wavelength: 358 nm) ofPCBBi1BP (abbreviation) is shown in FIG. 13A. In addition, an emissionspectrum of the thin film (excitation wavelength: 366 nm) of PCBBi1BP(abbreviation) is shown FIG. 13B. In FIGS. 13A and 13B, the horizontalaxis indicates the wavelength (nm) and the vertical axis indicates thelight emission intensity (arbitrary unit). The maximum emissionwavelength was 399 nm (excitation wavelength: 358 nm) in the case of thetoluene solution and 417 nm (excitation wavelength: 366 nm) in the caseof the thin film.

An oxidation-reduction reaction characteristic of PCBBi1BP(abbreviation) was examined by a cyclic voltammetry (CV) measurement.Since the measurement method is similar to that of Embodiment 1, thedescription is omitted.

FIG. 42 shows the CV measurement result on the oxidation reactioncharacteristics. As shown in FIG. 42, an oxidization peak potentialE_(pa) can be read as 0.521 V, and a reduction peak potential E_(pc) canbe read as +0.431 V. Therefore, a half-wave potential (an intermediatepotential between E_(pc) and E_(pa)) can be calculated to be +0.48 V.According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBBi1BP (abbreviation) was found to be=−5.42 [eV]. Inaddition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBBi1BP (abbreviation) was −5.34 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.15 eV. Thus, the energy gap in the solid statewas estimated to be 3.15 eV, which means that the LUMO level of PCBBi1BP(abbreviation) is −2.19 eV.

In addition, the glass transition temperature of PCBBi1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 123° C.In this manner, PCBBi1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBBi1BP(abbreviation) is a substance which is hard to be crystallized.

Embodiment 3

In Embodiment 3, a synthetic method of a carbazole derivative of thepresent invention,9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(abbreviation: PCBAF) represented by a structural formula (7), will bespecifically described.

Step 1: Synthesis of 2-bromo-9,9-dimethylfluoren

A synthetic scheme of 2-bromo-9,9-dimethylfluoren in Step 1 is shown inthe following (F-1).

In a 500-mL conical flask, 12.5 g (51 mmol) of 2-bromofluorene, 8.5 g(51 mmol) of potassium iodide, 14.3 g (0.50 mol) of potassium hydroxide,and 250 mL of dimethyl sulfoxide were stirred for 30 minutes. Then, 10mL of methyl iodide was added to this mixture little by little. Thismixture was stirred at room temperature for 48 hours. After thereaction, 400 mL of chloroform was added to the reaction solution andthis mixture was stirred. This solution was washed with 1N hydrochloricacid, a saturated sodium carbonate solution, and a saturated salinesolution in this order. Magnesium sulfate was added to the obtainedorganic layer to remove moisture.

This mixture was subjected to suction filtration and concentrated. Then,a residue thereof was purified by silica gel column chromatography. Thesilica gel column chromatography was performed by, first, using hexaneas a developing solvent, and then using a mixture solvent of ethylacetate:hexane=1:5 as another developing solvent. The correspondingfractions were concentrated and dried to obtain 12 g of a brown oilysubstance at a yield of 97%.

Step 2: Synthesis of9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(Abbreviation: PCBAF)

A synthetic scheme of9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(abbreviation: PCBAF) in Step 2 is shown in the following (F-2).

In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA), 1.3 g(4.9 mmol) of 2-bromo-9,9-dimethylfluoren, and 2.0 g (20 mmol) of sodiumtert-butoxide were put, and the atmosphere in the flask was substitutedby nitrogen. Note that since a synthetic method of PCBA (abbreviation)is similar to that described in Embodiment 2, the description is to bereferred thereto; thus, description here is omitted. Then, 50 mL oftoluene and 0.30 mL of tri(tert-butyl)phosphine (10 wt % hexanesolution) were added to this mixture. The mixture was deaerated whilebeing stirred under low pressure. After the deaeration, 0.10 g ofbis(dibenzylideneacetone)palladium(0) was added thereto. Next, themixture was stirred at 80° C. for 5 hours to be reacted. After thereaction, toluene was added to the reaction mixture, and suctionfiltration was performed on this suspension through Celite, alumina, andthen Florisil to obtain filtrate.

The obtained filtrate was concentrated and purified by silica gel columnchromatography. The silica gel column chromatography was performed by,first, using a mixture solvent of toluene:hexane=1:9 as a developingsolvent, and then using a mixture solvent of toluene:hexane=3:7 asanother developing solvent. A solid which was obtained by concentratingthe obtained fraction was recrystallized with a mixture solvent ofchloroform and hexane to obtain 1.3 g of an objective compound at ayield of 44%.

Sublimation purification of 1.3 g of the obtained light yellow solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa, with a flow rate ofargon at 3 mL/min, at 270° C. for 20 hours. Accordingly, 1.0 g of thelight yellow solid was obtained at a yield of 77%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 14A and 14B. Itwas found from the measurement result that the carbazole derivative ofthe present invention,9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(abbreviation: PCBAF) represented by the above structural formula (7),was obtained.

¹H NMR (DMSO-d, 300 MHz): δ (ppm)=1.39 (s, 6H) 6.98-7.82 (m, 26H), 8.35(d, J=6.8 Hz, 1H), 8.57 (s, 1H).

In addition, an absorption spectrum of a toluene solution of PCBAF(abbreviation) is shown in FIG. 15A. In addition, an absorption spectrumof a thin film of PCBAF (abbreviation) is shown in FIG. 15B. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for the measurement. The spectrum of the solutionwas measured in a quartz cell. The sample of the thin film wasfabricated by vapor evaporation of PCBAF (abbreviation) over a quartzsubstrate. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured sample is shown in FIG.15A, and the absorption spectrum of the thin film which was obtained bysubtracting the quartz substrate from the measured sample is shown inFIG. 15B. In FIGS. 15A and 15B, the horizontal axis indicates thewavelength (nm) and the vertical axis indicates the absorption intensity(arbitrary unit). In the case of the toluene solution, an absorptionpeak was observed at around 339 nm, and in the case of the thin film, anabsorption peak was observed at around 345 nm. In addition, an emissionspectrum of the toluene solution (excitation wavelength: 347 nm) ofPCBAF (abbreviation) is shown in FIG. 15A. In addition, an emissionspectrum of the thin film (excitation wavelength: 370 nm) of PCBAF(abbreviation) is shown FIG. 15B. In FIGS. 15A and 15B, the horizontalaxis indicates the wavelength (nm) and the vertical axis indicates thelight emission intensity (arbitrary unit). The maximum emissionwavelength was 394 nm (excitation wavelength: 347 nm) in the case of thetoluene solution and 404 nm (excitation wavelength: 370 nm) in the caseof the thin film.

An oxidation-reduction reaction characteristic of PCBAF (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

FIG. 43 shows the CV measurement result on the oxidation reactioncharacteristics. As shown in FIG. 43, an oxidization peak potentialE_(pa) can be read as 0.481 V, and a reduction peak potential E_(pc) canbe read as +0.393 V. Therefore, a half-wave potential (an intermediatepotential between E_(pc) and E_(pa)) can be calculated to be +0.44 V.According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBAF (abbreviation) was found to be=−5.38 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

Embodiment 4

In Embodiment 4, a synthetic method of a carbazole derivative of thepresent invention,N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF) represented by a structural formula (8), will bespecifically described.

Step 1-1: Synthesis of 9-(biphenyl-2-yl)-2-bromofluoren-9-ol

A synthetic scheme of 9-(biphenyl-2-yl)-2-bromofluoren-9-ol in Step 1-1is shown in the following (G-1-1).

In a 100-mL three-neck flask to which a dropping funnel and a Dimrothcondenser were connected, 1.26 g (0.052 mol) of magnesium was put, andthe flask was evacuated. The magnesium was activated by heating andstirring for 30 minutes. After cooling to room temperature, the flaskwas placed under a nitrogen gas flow. Then, 5 mL of diethyl ether andseveral drops of dibromoethane were added thereto, and 11.65 g (0.050mol) of 2-bromobiphenyl dissolved in 15 mL of diethyl ether was slowlydropped from the dropping funnel into the mixture. After completion ofthe dropping, the mixture was refluxed for 3 hours and made into aGrignard reagent.

In a 200-mL three-neck flask to which a dropping funnel and a Dimrothcondenser were connected, 11.7 g (0.045 mol) of 2-bromo-9-fluorenone and40 mL of diethyl ether were put. To this reaction solution, thesynthesized Grignard reagent was slowly dropped from the droppingfunnel. After completion of the dropping, the mixture was refluxed for 2hours, and then stirred at room temperature overnight. After completionof the reaction, the solution was washed twice with a saturated ammoniachloride solution, and separated into an aqueous layer and an organiclayer. The obtained aqueous layer was extracted twice with ethylacetate, and this ethyl acetate solution and the obtained organic layerwere washed with a saturated saline solution. After moisture was removedby magnesium sulfate, suction filtration and concentration wereperformed to obtain 18.76 g of a solid of9-(biphenyl-2-yl)-2-bromo-9-fluorenol at a yield of 90%.

Step 1-2: Synthesis of 2-bromo-spiro-9,9′-bifluoren

A synthetic scheme of 2-bromo-spiro-9,9′-bifluoren in Step 1-2 is shownin the following (G-1-2).

In a 200-mL three-neck flask, 18.76 g (0.045 mol) of the synthesized9-(biphenyl-2-yl)-2-bromo-9-fluorenol and 100 mL of glacial acetic acidwere put, several drops of concentrated hydrochloric acid were addedthereto, and the mixture was refluxed for 2 hours. After completion ofthe reaction, a precipitate was collected by suction filtration, and theprecipitate was filtered and washed with a saturated sodium hydrogencarbonate solution and water. The obtained brown solid wasrecrystallized with ethanol to obtain 10.24 g of a light-brownpowder-like solid at a yield of 57%.

Step 2: Synthesis ofN-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(Abbreviation: PCBASF)

A synthetic scheme ofN-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF) in Step 2 is shown in the following (G-2).

In a 100-mL three-neck flask, 2.0 g (4.9 mmol) of4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (abbreviation: PCBA), 1.9 g(4.9 mmol) of 2-bromo-spiro-9,9′-bifluoren, and 2.0 g (20 mmol) ofsodium tert-butoxide were put, and the atmosphere in the flask wassubstituted by nitrogen. Then, 50 mL of toluene and 0.30 mL oftri(tert-butyl)phosphine (10 wt % hexane solution) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, 0.10 g ofbis(dibenzylideneacetone)palladium(0) was added thereto.

Next, this mixture was stirred at 80° C. for 5 hours to be reacted.After the reaction, toluene was added to the reaction mixture, andsuction filtration was performed on this suspension through Celite,alumina, and then Florisil to obtain filtrate. The obtained filtrate waswashed with a saturated sodium carbonate solution and a saturated salinesolution in this order. After magnesium sulfate was added to an organiclayer to remove moisture, suction filtration was performed on thismixture and the magnesium sulfate was removed to obtain filtrate. Asolid which was obtained by concentrating the obtained filtrate wasrecrystallized with a mixture solvent of chloroform and hexane to obtain3.4 g of a white powder-like solid at a yield of 94%. Sublimationpurification of 2.3 g of the obtained white solid was performed by atrain sublimation method. The sublimation purification was performedunder a reduced pressure of 7.0 Pa, with a flow rate of argon at 3mL/min, at 310° C. for 20 hours. Accordingly, 1.7 g of the white solidwas obtained at a yield of 74%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 16A and 16B. Itwas found from the measurement result that the carbazole derivative ofthe present invention,N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF) represented by the above structural formula (8),was obtained.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=6.61-6.70 (m, 2H), 6.83 (d, J=8.3 Hz,2H), 6.88-7.79 (m, 30H), 8.16 (d, J=8.3 Hz, 1H), 8.26 (s, 1H).

In addition, an absorption spectrum of a toluene solution of PCBASF(abbreviation) is shown in FIG. 17A. In addition, an absorption spectrumof a thin film of PCBASF (abbreviation) is shown in FIG. 17B. Anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) was used for the measurement. The spectrum of the solutionwas measured in a quartz cell. The sample of the thin film wasfabricated by vapor evaporation of PCBASF (abbreviation) over a quartzsubstrate. The absorption spectrum of the solution which was obtained bysubtracting the quartz cell from the measured sample is shown in FIG.17A, and the absorption spectrum of the thin film which was obtained bysubtracting the quartz substrate from the measured sample is shown inFIG. 17B. In FIGS. 17A and 17B, the horizontal axis indicates thewavelength (nm) and the vertical axis indicates the absorption intensity(arbitrary unit). In the case of the toluene solution, an absorptionpeak was observed at around 338 nm, and in the case of the thin film, anabsorption peak was observed at around 345 nm. In addition, an emissionspectrum of the toluene solution (excitation wavelength: 352 nm) ofPCBASF (abbreviation) is shown in FIG. 17A. In addition, an emissionspectrum of the thin film (excitation wavelength: 371 nm) of PCBASF(abbreviation) is shown FIG. 17B. In FIGS. 17A and 17B, the horizontalaxis indicates the wavelength (nm) and the vertical axis indicates thelight emission intensity (arbitrary unit). The maximum emissionwavelength was 396 nm (excitation wavelength: 352 nm) in the case of thetoluene solution and 427 nm (excitation wavelength: 371 nm) in the caseof the thin film.

An oxidation-reduction reaction characteristic of PCBASF (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

FIG. 44 shows the CV measurement result on the oxidation reactioncharacteristics. As shown in FIG. 44, an oxidization peak potentialE_(pa) can be read as 0.52 V, and a reduction peak potential E_(pc) canbe read as +0.428 V. Therefore, a half-wave potential (an intermediatepotential between E_(pc) and E_(pa)) can be calculated to be +0.47 V.According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBASF (abbreviation) was found to be=−5.41 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

Embodiment 5

In Embodiment 5, a method for manufacturing a light-emitting element 2,a light-emitting element 3, a light-emitting element 4, and alight-emitting element 5, which were formed using carbazole derivativesof the present invention that are synthesized in Embodiments 1 to 4 andmeasurement results of their element characteristics will be described.The light-emitting element 2 was formed using4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP), the light-emitting element 3 was formed using4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP), the light-emitting element 4 was formed using9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(abbreviation: PCBAF), and the light-emitting element 5 was formed usingN-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF).

Note that each element structure of the light-emitting elements inEmbodiment 5 is a structure shown in FIG. 18, in which ahole-transporting layer 1512 is formed using the above carbazolederivative of the present invention. In addition, a light-emittingelement 1 which is a comparative light-emitting element is formed using4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) forthe hole-transporting layer 1512. In order to make comparativeconditions of the light-emitting element 1 with each of thelight-emitting elements 2 to 5 the same, the light-emitting element 1was formed over the same substrates as the light-emitting elements 2 to5, and the light-emitting element 1 was compared to the light-emittingelements 2 to 5. A structural formula of an organic compound used inEmbodiment 5 is shown below.

First, indium tin oxide containing silicon oxide was deposited over asubstrate 1501 which is a glass substrate by a sputtering method to forma first electrode 1502. The thickness of the first electrode 1502 wasset to be 110 nm, and the area was set to be 2 mm×2 mm.

Next, an EL layer 1503 in which a plurality of layers are stacked overthe first electrode 1502 was formed. In Embodiment 5, the EL layer 1503has a structure in which a first layer 1511 which is a hole-injectinglayer, a second layer 1512 which is a hole-transporting layer, a thirdlayer 1513 which is a light-emitting layer, a fourth layer 1514 which isan electron-transporting layer, and a fifth layer 1515 which is anelectron-injecting layer are sequentially stacked.

The substrate having the first electrode 1502 was fixed to a substrateholder provided in a vacuum evaporation apparatus in such a way that thesurface of the first electrode 1502 faced downward, and then thepressure was reduced to about 10⁻⁴ Pa. Then,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) andmolybdenum(VI) oxide were co-evaporated on the first electrode 1502,whereby the first layer 1511 which is a hole-injecting layer was formed.The evaporation rate was controlled so that the thickness of the firstlayer which is a hole-injecting layer could be 50 nm and the weightratio of NPB to molybdenum(VI) oxide could be 4:1 (=NPB: molybdenumoxide). Note that the co-evaporation method is an evaporation method inwhich evaporation is performed using a plurality of evaporation sourcesat the same time in one treatment chamber.

Next, a hole-transporting material was deposited over the first layer1511 to a thickness of 10 nm by an evaporation method using resistiveheating, and the second layer 1512 which is a hole-transporting layerwas formed. Note that 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl(abbreviation: NPB) was used in the case of forming the light-emittingelement 1, 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBA1BP) was used in the case of forming thelight-emitting element 2,4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP) was used in the case of forming thelight-emitting element 3,9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-fluorene-2-amine(abbreviation: PCBAF) was used in the case of forming the light-emittingelement 4, andN-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9-bifluoren-2-amine(abbreviation: PCBASF) were used in the case of forming thelight-emitting element 5.

Next, the third layer 1513 which is a light-emitting layer was formedover the second layer 1512 by an evaporation method using resistiveheating. The third layer 1513 was formed by co-evaporating9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA) and4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA) to a thickness of 30 nm. Here, the evaporationrate was controlled so that the weight ratio of CzPA to PCBAPA could be1:0.10 (=CzPA: PCBAPA).

Further, tris(8-quinolinolato)aluminum(III) (abbreviation: Alq) wasdeposited over the third layer 1513 to be a thickness of 10 nm by anevaporation method using resistive heating. Then, the fourth layer 1514which is an electron-transporting layer was formed by depositingbathophenanthroline (abbreviation: BPhen) over the third layer 1513 to athickness of 20 nm.

Then, the fifth layer 1515 which is an electron-injecting layer wasformed by depositing lithium fluoride (LiF) to a thickness of 1 nm overthe fourth layer 1514.

Finally, a second electrode 1504 was formed by depositing aluminum to athickness of 200 nm by an evaporation method using resistance heating,and the light-emitting elements 1 to 5 were formed.

The light-emitting elements 1 to 5 obtained through the processdescribed above were put into a glove box with a nitrogen atmosphere sothat the light-emitting elements were sealed without being exposed toatmospheric air. After that, the operating characteristics of theselight-emitting elements were measured. Note that the measurement wasperformed at room temperature (an atmosphere kept at 25° C.).

FIG. 19 shows the current density vs. luminance characteristics of thelight-emitting elements 1 and 2. FIG. 20 shows the voltage vs. luminancecharacteristics of the light-emitting elements 1 and 2. FIG. 21 showsthe luminance vs. current efficiency characteristics of thelight-emitting elements 1 and 2. FIG. 22 shows the voltage vs. currentcharacteristics of the light-emitting elements 1 and 2.

When the drive voltage of the light-emitting element 2 was 3.4 V, theluminance and the current value were 1277 cd/m² and 0.79 mA,respectively. It was found that the light-emitting element 2 usingPCBA1BP (abbreviation) for the second layer 1512 showed higherluminance, even when the light-emitting element 2 was compared to thelight-emitting element 1 using NPB for the second layer 1512. Further,it was found that the current efficiency was high with respect to thecurrent density or the luminance.

In addition, in the light-emitting element 2, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 23. Thus, it wasfound that favorable carrier balance was realized in the structure ofthe light-emitting element 2 using PCBA1BP (abbreviation) of the presentinvention.

FIG. 24 shows the results of a continuous lighting test in which thelight-emitting element 2 was continuously lit by constant currentdriving with the initial luminance set at 1000 cd/m² (the vertical axisindicates the relative luminance on the assumption that 1000 cd/m² is100%). From the results in FIG. 24, the light-emitting element 2exhibits 92% of the initial luminance even after 160 hours, and wasfound to have a longer lifetime, as compared to the light-emittingelement 1. Thus, a long lifetime light-emitting element can be obtainedby applying PCBA1BP (abbreviation) of the present invention.

FIG. 25 shows the current density vs. luminance characteristics of thelight-emitting elements 1 and 3. FIG. 26 shows the voltage vs. luminancecharacteristics of the light-emitting elements 1 and 3. FIG. 27 showsthe luminance vs. current efficiency characteristics of thelight-emitting elements 1 and 3. FIG. 28 shows the voltage vs. currentcharacteristics of the light-emitting elements 1 and 3.

When the drive voltage of the light-emitting element 3 was 3.4 V, theluminance and the current value were 1328 cd/m² and 0.78 mA,respectively. It was found that the light-emitting element 3 usingPCBBi1BP (abbreviation) for the second layer 1512 showed higherluminance, even when the light-emitting element 3 was compared to thelight-emitting element 1 using NPB for the second layer 1512. Further,it was found that the current efficiency was high with respect to thecurrent density or the luminance.

In addition, in the light-emitting element 3, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 29. Thus, it wasfound that favorable carrier balance was realized in the structure ofthe light-emitting element 3 using PCBBi1BP (abbreviation) of thepresent invention.

FIG. 30 shows the current density vs. luminance characteristics of thelight-emitting elements 1 and 4. FIG. 31 shows the voltage vs. luminancecharacteristics of the light-emitting elements 1 and 4. FIG. 32 showsthe luminance vs. current efficiency characteristics of thelight-emitting elements 1 and 4. FIG. 33 shows the voltage vs. currentcharacteristics of the light-emitting elements 1 and 4.

When the drive voltage of the light-emitting element 4 was 3.8 V, theluminance and the current value were 1328 cd/m² and 1.08 mA,respectively. It was found that the light-emitting element 4 using PCBAF(abbreviation) for the second layer 1512 showed higher luminance, evenwhen the light-emitting element 4 was compared to the light-emittingelement 1 using NPB for the second layer 1512.

In addition, in the light-emitting element 4, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 34. Thus, it wasfound that favorable carrier balance was realized in the structure ofthe light-emitting element 4 using PCBAF (abbreviation) of the presentinvention.

FIG. 35 shows the results of a continuous lighting test in which thelight-emitting element 4 was continuously lit by constant currentdriving with the initial luminance set at 1000 cd/m² (the vertical axisindicates the relative luminance on the assumption that 1000 cd/m² is100%). From the results in FIG. 35, the light-emitting element 4exhibits 92% of the initial luminance even after 160 hours and was foundto have a longer lifetime, as compared to the light-emitting element 1.Thus, a long lifetime light-emitting element can be obtained by applyingPCBAF (abbreviation) of the present invention.

FIG. 36 shows the current density vs. luminance characteristics of thelight-emitting elements 1 and 5. FIG. 37 shows the voltage vs. luminancecharacteristics of the light-emitting elements 1 and 5. FIG. 38 showsthe luminance vs. current efficiency characteristics of thelight-emitting elements 1 and 5. FIG. 39 shows the voltage vs. currentcharacteristics of the light-emitting elements 1 and 5.

When the drive voltage of the light-emitting element 5 was 3.8 V, theluminance and the current value were 1398 cd/m² and 1.11 mA,respectively. It was found that the light-emitting element 5 usingPCBASF (abbreviation) for the second layer 1512 showed higher luminance,even when the light-emitting element 5 was compared to thelight-emitting element 1 using NPB for the second layer 1512. Further,it was found that the current efficiency was high with respect to thecurrent density or the luminance.

In addition, in the light-emitting element 5, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 40. Thus, it wasfound that favorable carrier balance was realized in the structure ofthe light-emitting element 5 using PCBASF (abbreviation) of the presentinvention.

As described above, it was found that the light-emitting elements 2 to 5which were formed using the carbazole derivatives of the presentinvention exhibited an equivalent level of efficiency to thelight-emitting element 1. Thus, it was found that a light-emittingelement having high efficiency can be obtained by applying the presentinvention.

In addition, as another structure of the light-emitting element 1 shownin Embodiment 5, PCBA1BP (abbreviation) was used instead of NPB(abbreviation), which was used at the time of forming the first layer1511, and was co-evaporated with molybdenum(VI) oxide to form the firstlayer 1511. With the efficiency, the drive voltage at a luminance ofabout 1000 cd/m², and the reliability of such a light-emitting element1, favorable values equivalent to those of a light-emitting element 8were obtained. The light-emitting element 8 will be formed in Embodiment10 by using a co-evaporation film of NPB and molybdenum(VI) oxide for ahole-injecting layer and using PCBBiNB (abbreviation) for ahole-transporting layer. When the drive voltage of the light-emittingelement 1 was 3.8 V, the luminance and the current value were 949 cd/m²and 0.65 mA, respectively, and the light-emitting element 1 exhibited64% of the initial luminance when driven for 1500 hours.

As thus described, it was found that PCBA1BP (abbreviation) was afavorable material also as a hole-injecting material. In addition, itwas found that favorable characteristics can also be obtained by usingthe co-evaporation film with molybdenum(VI) oxide for the hole-injectinglayer.

In addition, as another structure of the light-emitting element 2 shownin Embodiment 5, PCBA1BP (abbreviation) was used instead of NPB(abbreviation), which was used at the time of forming the first layer1511, and was co-evaporated with molybdenum(VI) oxide to form the firstlayer 1511. With the efficiency, the drive voltage at a luminance ofabout 1000 cd/m², and the reliability of such a light-emitting element2, favorable values equivalent to those of a light-emitting element 8were obtained. The light-emitting element 8 will be formed in Embodiment10 by using a co-evaporation film of NPB and molybdenum(VI) oxide for ahole-injecting layer and using PCBBiNB (abbreviation) for ahole-transporting layer. When the drive voltage of the light-emittingelement 2 was 3.6 V, the luminance and the current value were 843 cd/m²and 0.53 mA, respectively, and the light-emitting element 2 exhibited65% of the initial luminance when driven for 1500 hours.

As thus described, it was found that PCBA1BP (abbreviation) was afavorable material which can be used for both the first layer 1511 whichis a hole-injecting layer and the second layer 1512 which is ahole-transporting layer at the same time. Accordingly, an element couldbe manufactured easily and material use efficiency could also beimproved.

Embodiment 6

In Embodiment 6, a synthetic method of a carbazole derivative of thepresent invention,(biphenyl-4-yl)(phenyl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine(abbreviation: PCTA1BP) represented by a structural formula (15), willbe specifically described.

Step 1: Synthesis of 4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronicAcid

A synthetic scheme of 4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronicacid in Step 1 is shown in the following (H-1).

In a 300-mL three-neck flask, 7.0 g (18 mmol) of4-bromo-4′-phenyltriphenylamine was put, and the atmosphere in the flaskwas substituted by nitrogen. Then, 80 mL of tetrahydrofuran(abbreviation: THF) was added thereto, and the mixture was stirred at−78° C. for 10 minutes. After that, 13 mL (21 mmol) of an n-butyllithiumhexane solution (1.63 mol/L) was dropped onto this solution from asyringe, and the solution was stirred at −78° C. for 1 hour. After thestirring, 3.5 mL (31 mmol) of trimethyl borate was added to the reactionmixture, and the mixture was stirred at −78° C. for 1 hour and at roomtemperature for 24 hours. After the reaction, 100 mL of 1M dilutehydrochloric acid was added to the reaction solution, and the mixturewas stirred at room temperature for 1 hour. After the stirring, thissolution was extracted with ethyl acetate, and an organic layer waswashed with a saturated saline solution. After the washing, magnesiumsulfate was added to the organic layer, and the organic layer was dried.After the drying, magnesium sulfate was removed by suction filtration toobtain filtrate. The obtained filtrate was concentrated andrecrystallized with a mixture solvent of chloroform and hexane to obtain3.6 g of an object at a yield of 56%.

Step 2: Synthesis of(biphenyl-4-yl)(phenyl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine(Abbreviation: PCTA1BP)

A synthetic scheme of(biphenyl-4-yl)(phenyl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]aminein Step 2 is shown in the following (H-2).

In a 100-mL three-neck flask, 2.2 g (5.5 mmol) of4-[N-(biphenyl-4-yl)-N-phenyl]aminophenylboronic acid, 2.0 g (5.5 mmol)of 3-(4-bromophenyl)-9-phenyl-9H-carbazole, 10 mg (0.045 mmol) ofpalladium(II) acetate, and 0.69 g (0.23 mmol) of tri(o-tolyl)phosphinewere put, and 10 mL of a potassium carbonate solution (2.0 mol/L) and 20mL of ethylene glycol dimethyl ether (abbreviation: DME) were addedthereto. This mixture was deaerated while being stirred under lowpressure, and the atmosphere in the flask was substituted by nitrogen.This mixture was stirred at 90° C. for 5 hours. After the stirring,toluene was added to the reaction mixture, and the mixture was heated at90° C.

After the heating, this suspension was separated into an organic layerand an aqueous layer. After the separation, the organic layer was washedwith a saturated sodium hydrogen carbonate solution and a saturatedsaline solution. Magnesium sulfate was added to the organic layer, andthe organic layer was dried. Suction filtration was performed on thismixture through Celite, alumina, and then Florisil to obtain filtrate.The obtained filtrate was concentrated to obtain a solid. The obtainedfiltrate was dissolved and purified by silica gel column chromatography.The silica gel column chromatography was performed by, first, using amixture solvent of toluene: hexane=1:9 as a developing solvent, and thenusing a mixture solvent of toluene:hexane=2:3 as another developingsolvent. A solid which was obtained by concentrating the obtainedfraction was dissolved in chloroform and purified by high performanceliquid chromatography (HPLC) (developing solvent, chloroform). A solidwhich was obtained by concentrating the obtained fraction wasrecrystallized with a mixture solvent of chloroform and hexane to obtain1.7 g of an objective white solid at a yield of 48%.

Sublimation purification of 1.0 g of the obtained white solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa, with a flow rate ofargon at 4 mL/min, at 300° C. for 15 hours to obtain 0.62 g of the whitesolid at a yield of 62%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 45A and 45B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCTA1BP (abbreviation) represented by the abovestructural formula (15), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.02-7.79 (m, 32H), 8.19 (d, J=7.3 Hz, 1H), 8.39 (s, 1H).

In addition, an absorption spectrum of PCTA1BP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 349 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 357 nm.

In addition, an emission spectrum of PCTA1BP (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 405 nm (excitationwavelength: 320 nm), and in the case of the thin film, a maximumemission wavelength was 420 nm (excitation wavelength: 284 nm). Sincethe measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCTA1BP (abbreviation) was −5.49 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.10 eV. Thus, the energy gap in the solid statewas estimated to be 3.10 eV, which means that the LUMO level of PCTA1BP(abbreviation) is −2.39 eV.

An oxidation-reduction reaction characteristic of PCTA1BP (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted. According to the calculation similar to that of Embodiment1, the HOMO level of PCTA1BP (abbreviation) was found to be=−5.48 [eV].In addition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCTA1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 118° C.In this manner, PCTA1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCTA1BP(abbreviation) is a substance which is hard to be crystallized.

Note that with the efficiency, the drive voltage at a luminance of about1000 cd/m², and the reliability of a light-emitting element formed usingPCTA1BP (abbreviation) which was synthesized in Embodiment 6 in a mannersimilar to that of Embodiment 5 for a hole-transporting layer, favorablevalues equivalent to those of a light-emitting element 8 which will beformed using PCBBiNB in Embodiment 10 were obtained. When the drivevoltage of the light-emitting element was 3.6 V, the luminance and thecurrent value were 1044 cd/m² and 0.67 mA, respectively, and thelight-emitting element exhibited 52% of the initial luminance whendriven for 1100 hours.

Embodiment 7

In Embodiment 7, a synthetic method of a carbazole derivative of thepresent invention,bis(biphenyl-4-yl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine(abbreviation: PCTBi1BP) represented by a structural formula (190), willbe specifically described.

Step 1: Synthesis of 4-[(bis(biphenyl-4-yl)amino]phenylboronic Acid

A synthetic scheme of 4-[bis(biphenyl-4-yl)amino]phenylboronic acid inStep 1 is shown in the following (I-1).

In a 300-mL three-neck flask, 6.0 g (13 mmol) of4-bromo-4′,4″-diphenyltriphenylamine was put, and the atmosphere in theflask was substituted by nitrogen. Then, 80 mL of tetrahydrofuran(abbreviation: THF) was added thereto, and the mixture was stirred at−78° C. for 10 minutes. After that, 10 mL of an n-butyllithium hexanesolution (1.63 mol/L) was dropped onto this solution from a syringe, andthe solution was stirred at −78° C. for 1 hour. After the stirring, 2.8mL (25 mmol) of trimethyl borate was added to the reaction mixture, andthe mixture was stirred at −78° C. for 1 hour and further at roomtemperature for 24 hours. After the stirring, about 50 mL of dilutehydrochloric acid was added to the reaction mixture, and the mixture wasstirred at room temperature for 30 minutes. After the stirring, ethylacetate was added to this mixture to perform extraction. After theextraction, an organic layer was washed with a saturated salinesolution. Then, magnesium sulfate was added to the organic layer, andthe organic layer was dried. After the drying, suction filtration wasperformed on this mixture to obtain filtrate. The obtained filtrate wasconcentrated and recrystallized with a mixture solvent of chloroform andhexane to obtain 4.8 g of an objective white powder-like solid at ayield of 86%.

Step 2: Synthesis ofbis(biphenyl-4-yl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine(Abbreviation: PCTBi1BP)

A synthetic scheme ofbis(biphenyl-4-yl)[4′-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]amine inStep 2 is shown in the following (1-2).

In a 100-mL three-neck flask, 2.0 g (4.5 mmol) of4-[bis(biphenyl-4-yl)amino]phenylboronic acid, 1.8 g (4.5 mmol) of3-(4-bromophenyl)-9-phenyl-9H-carbazole, 10 mg (0.045 mmol) ofpalladium(II) acetate, and 0.69 g (0.23 mmol) of tri(o-tolyl)phosphinewere put, and 10 mL of a potassium carbonate solution (2.0 mol/L) and 20mL of ethylene glycol dimethyl ether (abbreviation: DME) were addedthereto. This mixture was deaerated while being stirred under lowpressure, and the atmosphere in the flask was substituted by nitrogen.This mixture was stirred at 90° C. for 5 hours. After the stirring,toluene was added to the reaction mixture, and the mixture was heated at90° C.

After the heating, this suspension was separated into an organic layerand an aqueous layer. After the separation, the organic layer was washedwith a saturated sodium hydrogen carbonate solution and a saturatedsaline solution. Magnesium sulfate was added to the organic layer, andthe organic layer was dried. Suction filtration was performed on thismixture through Celite, alumina, and then Florisil to obtain filtrate.The obtained filtrate was concentrated to obtain a solid. The obtainedfiltrate was dissolved in toluene and purified by silica gel columnchromatography. The silica gel column chromatography was performed byusing toluene as a developing solvent. A solid which was obtained byconcentrating the obtained fraction was recrystallized with a mixturesolvent of toluene and hexane to obtain 2.4 g of an objective whitesolid at a yield of 74%.

Sublimation purification of the obtained white solid was performed by atrain sublimation method. The sublimation purification was performedunder a reduced pressure of 7.0 Pa, with a flow rate of argon at 3mL/min, at 340° C. for 20 hours to obtain 0.70 g of the white solid, thetheoretical yield of which is 1.5 g, at a yield of 46%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 46A and 46B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCTBi1BP (abbreviation) represented by the abovestructural formula (190), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.18-7.83 (m, 36H), 8.21 (d, J=7.3 Hz, 1H), 8.40 (s, 1H).

In addition, an absorption spectrum of PCTBi1BP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 350 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 357 nm.

In addition, an emission spectrum of PCTBi1BP (abbreviation)(measurement range: 370 nm to 550 nm) was measured. In the case of thetoluene solution, a maximum emission wavelength was 410 nm (excitationwavelength: 320 nm), and in the case of the thin film, a maximumemission wavelength was 447 nm (excitation wavelength: 340 nm). Sincethe measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCTBi1BP (abbreviation) was −5.50 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.14 eV. Thus, the energy gap in the solid statewas estimated to be 3.14 eV, which means that the LUMO level of PCTBi1BP(abbreviation) is −2.36 eV.

An oxidation-reduction reaction characteristic of PCTBi1BP(abbreviation) was examined by a cyclic voltammetry (CV) measurement.Since the measurement method is similar to that of Embodiment 1, thedescription is omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCTBi1BP (abbreviation) was found to be=−5.46 [eV]. Inaddition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCTBi1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 133° C.In this manner, PCTBi1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCTBi1BP(abbreviation) is a substance which is hard to be crystallized.

Note that with the efficiency, the drive voltage at a luminance of about1000 cd/m², and the reliability of a light-emitting element formed usingPCTBi1BP (abbreviation) which was synthesized in Embodiment 7 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of a light-emitting element 8 whichwill be formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 3.6 V, the luminance andthe current value were 873 cd/m² and 0.56 mA, respectively, and thelight-emitting element exhibited 80% of the initial luminance whendriven for 110 hours.

Embodiment 8

In Embodiment 8, a synthetic method of a carbazole derivative of thepresent invention,4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBANB) represented by a structural formula (343), willbe specifically described.

Step 1: Synthesis of 3-(4-bromophenyl)-9-phenyl-9H-carbazole

A synthetic scheme of 3-(4-bromophenyl)-9-phenyl-9H-carbazole in Step 1is shown in the following (J-1).

In a 200-mL three-neck flask, 3.7 g (9.9 mmol) of3-iodo-9-phenyl-9H-carbazole, 2.0 g (9.9 mmol) of 4-bromo phenylboronicacid, and 0.61 g (2.0 mmol) of tri(o-tolyl)phosphine were put, and 50 mLof ethylene glycol dimethyl ether (abbreviation: DME) and 10 mL of apotassium carbonate solution (2 mol/L) were added to this mixture. Thismixture was deaerated while being stirred under low pressure, and theatmosphere in the flask was substituted by nitrogen after thedeaeration.

Then, 0.11 g (0.50 mmol) of palladium(II) acetate was added to thismixture. This mixture was stirred at 80° C. for 9.5 hours. After thestirring, this mixture was cooled to room temperature and then washedtwice with water. The obtained aqueous layer was extracted twice withtoluene. Then, the extracted solution was combined with an organiclayer, followed by washing with a saturated saline solution. The organiclayer was dried with magnesium sulfate, this mixture was naturallyfiltrated, and then the filtrate was concentrated.

The obtained oily substance was dissolved in about 20 mL of toluene, andsuction filtration was performed on this solution through Celite,alumina, and then Florisil. A solid which was obtained by concentratingthe obtained filtrate was purified by silica gel column chromatography(developing solvent, toluene:hexane=1:4) to obtain 1.9 g of an objectivewhite powder-like solid at a yield of 49%.

Step 2: Synthesis of 4-(1-naphthyl)diphenylamine

A synthetic scheme of 4-(1-naphthyl)diphenylamine in Step 2 is shown inthe following (J-2).

In a 200-mL three-neck flask, 12 g (50 mmol) of 4-bromodiphenylamine,8.6 g (50 mmol) of 1-naphthaleneboronic acid, 22 mg (0.1 mmol) ofpalladium(II) acetate, and 60 mg (0.2 mmol) of tri(o-tolyl)phosphinewere put, and 50 mL of toluene, 20 mL of ethanol, and 35 mL of apotassium carbonate solution (2 mol/L) were added to this mixture. Thismixture was deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 2 hours to be reacted.

After the reaction, 100 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was concentratedand purified by silica gel column chromatography (developing solvent,toluene:hexane:ethyl acetate=1:8:1). The obtained fraction wasconcentrated, and methanol was added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 3.0 g of an objectivewhite powder at a yield of 20%.

Step 3: Synthesis of4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(Abbreviation: PCBANB)

A synthetic scheme of4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine in Step 3is shown in the following (J-3).

In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of3-(4-bromophenyl)-9-phenyl-9H-carbazole, 0.9 g (3.0 mmol) of4-(1-naphthyl)diphenylamine, 0.5 g (5.0 mmol) of sodium tert-butoxide,and 6.0 mg (0.01 mmol) of bis(dibenzylideneacetone)palladium(0) wereput, and 15 mL of dehydrated xylene was added to this mixture. Thismixture was deaerated while being stirred under low pressure. After thedeaeration, 0.06 mL (0.03 mmol) of tri(tert-butyl)phosphine (10 wt %hexane solution) was added thereto. This mixture was stirred under anitrogen atmosphere at 120° C. for 4.5 hours to be reacted.

After the reaction, 250 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,alumina, and then Celite. The obtained filtrate was washed with water.Then, magnesium sulfate was added to remove moisture. This suspensionwas filtrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 1.5 g of an objective white powder ata yield of 82%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane 1:10) was0.34, that of 3-(4-bromophenyl)-9-phenyl-9H-carbazole was 0.46, and thatof 4-(1-naphthyl)diphenylamine was 0.25.

A compound which was obtained through the above Step 3 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 47A and 47B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBANB (abbreviation) represented by the abovestructural formula (343), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.07 (t, J=6.6 Hz, 1H), 7.25-7.67 (m, 26H), 7.84 (d, J=7.8 Hz,1H), 7.89-7.92 (m, 1H), 8.03-8.07 (m, 1H), 8.18 (d, J=7.8 Hz, 1H), 8.35(d, J=0.9 Hz, 1H).

In addition, an absorption spectrum of PCBANB (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 335 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 341 nm.

In addition, an emission spectrum of PCBANB (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 410 nm (excitationwavelength: 345 nm), and in the case of the thin film, a maximumemission wavelength was 433 nm (excitation wavelength: 341 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBANB (abbreviation) was −5.44 eV. TheTauc plot of the absorption spectrum of the thin film revealed that theabsorption edge was 3.25 eV. Thus, the energy gap in the solid state wasestimated to be 3.25 eV, which means that the LUMO level of PCBANB(abbreviation) is −2.19 eV.

An oxidation-reduction reaction characteristic of PCBANB (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBANB (abbreviation) was found to be=−5.44 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBANB (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 115° C.In this manner, PCBANB (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBANB(abbreviation) is a substance which is hard to be crystallized.

In addition, FIGS. 56 to 59 show the measurement results in elementcharacteristics of the light-emitting element 6 which was formed using,for a hole-transporting layer, PCBANB (abbreviation) which is thecarbazole derivative of the present invention that was synthesized inEmbodiment 8 in a manner similar to that of Embodiment 5. It was foundthat the hole-transporting material of the present invention which wasused for the light-emitting element 6 showed higher luminance, even whenthe hole-transporting material of the present invention which was usedfor the light-emitting element 6 was compared to NPB of thelight-emitting element 1. Note that the light-emitting element 1 whichis a comparative light-emitting element was formed using4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) forthe hole-transporting layer 151 in a manner similar to that ofEmbodiment 5.

In addition, in the light-emitting element 6, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 59. Thus, it wasfound that the hole-transporting material of the present inventionrealizes favorable carrier balance in the structure of thelight-emitting element 6.

FIG. 60 shows the result of a continuous lighting test in which thelight-emitting element 6 was continuously lit by constant currentdriving with the initial luminance set at 1000 cd/m² (the vertical axisindicates the relative luminance on the assumption that 1000 cd/m² is100%). From the results in FIG. 60, the light-emitting element 6 wasfound to have a longer lifetime, as compared to the light-emittingelement 1. Thus, a long lifetime light-emitting element can be obtainedby applying the present invention.

Embodiment 9

In Embodiment 9, a synthetic method of a carbazole derivative of thepresent invention,4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBNBB) represented by a structural formula (229), willbe specifically described.

Step 1: Synthesis of 4,4′-dibromotriphenylamine

A synthetic scheme of 4,4′-dibromotriphenylamine in Step 1 is shown inthe following (K-1).

After 12 g (50 mmol) of triphenylamine was dissolved in a mixturesolvent of 250 mL of ethyl acetate in a 500-mL conical flask, 18 g (100mmol) of N-bromo succinimide (abbreviation: NBS) was added to thissolution. After that, this mixture was stirred at room temperature for24 hours. After completion of the reaction, this mixture solution waswashed with water, and magnesium sulfate was added thereto to removemoisture. This mixture solution was filtrated and the obtained filtratewas concentrated and dried to obtain 20 g of an objective white solid ata yield of 99%.

Step 2: Synthesis of 4,4′-di(1-naphthyl)triphenylamine

A synthetic scheme of 4,4′-di(1-naphthyl)triphenylamine in Step 2 isshown in the following (K-2).

In a 100-mL three-neck flask, 6.0 g (15 mmol) of4,4′-dibromotriphenylamine, 5.2 g (30 mmol) of 1-naphthaleneboronicacid, 2.0 mg (0.01 mmol) of palladium(II) acetate, and 6.0 mg (0.02mmol) of tri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL ofethanol, and 20 mL of a potassium carbonate solution (2 mol/L) wereadded to this mixture. This mixture was deaerated while being stirredunder low pressure. After the deaeration, the mixture was stirred undera nitrogen atmosphere at 90° C. for 4.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and on this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil, alumina, silica gel, and then Celite to obtainfiltrate. The obtained filtrate was concentrated, and methanol was addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 6.4 g of an objective white powder at a yieldof 86%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.53 and that of 4,4′-dibromotriphenylamine was 0.69.

Step 3: Synthesis of 4-bromo-4′,4″-di(1-naphthyl)triphenylamine

A synthetic scheme of 4-bromo-4′,4″-di(1-naphthyl)triphenylamine in Step3 is shown in the following (K-3).

After 6.4 g (13 mmol) of 4,4′-di(1-naphthyl)triphenylamine was dissolvedin 150 mL of ethyl acetate in a 300-mL conical flask, 2.3 g (13 mmol) ofN-bromo succinimide (abbreviation: NBS) was added to this solution.After that, this mixture was stirred at room temperature for 24 hours.After completion of the reaction, this mixture solution was washed withwater, and magnesium sulfate was added thereto to remove moisture. Thismixture solution was filtrated, the obtained filtrate was concentrated,and methanol was added thereto. The mixture was irradiated withsupersonic and then recrystallized to be purified by silica gel columnchromatography (developing solvent, toluene:hexane=1:5). Accordingly,1.6 g of an objective white powder was obtained at a yield of 22%.

Step 4: Synthesis of4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(Abbreviation: PCBNBB)

A synthetic scheme of4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine inStep 4 is shown in the following (K-4).

In a 50-mL three-neck flask, 1.4 g (2.5 mmol) of4-bromo-4′,4″-di(1-naphthyl)triphenylamine, 0.7 g (2.5 mmol) of9-phenyl-9H-carbazol-3-yl-boronic acid, 4.0 mg (0.02 mmol) ofpalladium(II) acetate, and 6.0 mg (0.02 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, 5 mL of ethanol, and 2.5 mL of apotassium carbonate solution (2 mol/L) were added to this mixture. Thismixture was deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil, alumina, silica gel, and then Celite to obtainfiltrate. The obtained filtrate was concentrated and purified by silicagel column chromatography (developing solvent, toluene:hexane=1:4). Theobtained fraction was concentrated, and methanol was added thereto. Themixture was irradiated with supersonic and then recrystallized to obtain0.4 g of an objective white powder at a yield of 22%.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 48A and 48B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBNBB (abbreviation) represented by the abovestructural formula (229), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.28-7.72 (m, 30H), 7.85 (d, J=7.8 Hz, 2H), 7.90-7.93 (m, 2H),8.06-8.09 (m, 2H), 8.19 (d, J=7.5 Hz, 1H), 8.38 (d, J=1.5 Hz, 1H).

In addition, an absorption spectrum of PCBNBB (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 345 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 355 nm.

In addition, an emission spectrum of PCBNBB (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 413 nm (excitationwavelength: 355 nm), and in the case of the thin film, a maximumemission wavelength was 428 nm (excitation wavelength: 370 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBNBB (abbreviation) was −5.46 eV. TheTauc plot of the absorption spectrum of the thin film revealed that theabsorption edge was 3.15 eV. Thus, the energy gap in the solid state wasestimated to be 3.15 eV, which means that the LUMO level of PCBNBB(abbreviation) is −2.31 eV.

An oxidation-reduction reaction characteristic of PCBNBB (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted. According to the calculation similar to that of Embodiment1, the HOMO level of PCBNBB (abbreviation) was found to be=−5.43 [eV].In addition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBNBB (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 136° C.In this manner, PCBNBB (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBNBB(abbreviation) is a substance which is hard to be crystallized.

In addition, FIGS. 56 to 59 show the measurement results in elementcharacteristics of the light-emitting element 7 which was formed using,for a hole-transporting layer, PCBNBB (abbreviation) which is thecarbazole derivative of the present invention that was synthesized inEmbodiment 9 in a manner similar to that of Embodiment 5. It was foundthat the hole-transporting material of the present invention which wasused for the light-emitting element 7 showed higher luminance, even whenthe hole-transporting material of the present invention which was usedfor the light-emitting element 7 was compared to NPB of thelight-emitting element 1. Note that the light-emitting element 1 whichis a comparative light-emitting element was formed using4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) forthe hole-transporting layer 151 in a manner similar to that ofEmbodiment 5.

In addition, in the light-emitting element 7, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 59. Thus, it wasfound that the hole-transporting material of the present inventionrealizes favorable carrier balance in the structure of thelight-emitting element 7.

FIG. 60 shows the result of a continuous lighting test in which thelight-emitting element 7 was continuously lit by constant currentdriving with the initial luminance set at 1000 cd/m² (the vertical axisindicates the relative luminance on the assumption that 1000 cd/m² is100%). From the results in FIG. 60, the light-emitting element 7 wasfound to have a longer lifetime, as compared to the light-emittingelement 1.

Embodiment 10

In Embodiment 10, a synthetic method of a carbazole derivative of thepresent invention,4-(1-naphthyl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBiNB) represented by a structural formula (220), willbe specifically described.

Step 1: Synthesis of 4-phenyltriphenylamine

A synthetic scheme of 4-phenyltriphenylamine in Step 1 is shown in thefollowing (L-1).

In a 300-mL three-neck flask, 9.3 g (40 mmol) of 4-bromophenyl, 6.8 g(40 mmol) of diphenylamine, 5.0 g (50 mol) of sodium tert-butoxide, and10 mg of bis(dibenzylideneacetone)palladium(0) were put, and theatmosphere in the flask was substituted by nitrogen. Then, 100 mL ofxylene and 0.6 mL of tri(tert-butyl)phosphine (10 wt % hexane solution)were added to this mixture.

This mixture was deaerated while being stirred under low pressure. Afterthe atmosphere was substituted by nitrogen, the mixture was stirred at130° C. for 3.5 hours. After the stirring, 250 mL of toluene was addedto the reaction mixture, and this suspension was filtrated throughCelite, alumina, and then Florisil. The obtained filtrate was washedwith water and dried, and magnesium sulfate was added thereto. Thismixture was filtrated through Celite, alumina, and then Florisil toobtain filtrate. The obtained filtrate was concentrated, and methanolwas added thereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 11 g of an objective white powder at a yield of89%.

Step 2: Synthesis of 4-bromo-4′-phenyltriphenylamine

A synthetic scheme of 4-bromo-4′-phenyltriphenylamine in Step 2 is shownin the following (L-2).

In a 500-mL conical flask, 6.4 g (20 mmol) of 4-phenyltriphenylamine,250 mL of ethyl acetate, and 150 mL of toluene were added and themixture was stirred, and then 3.6 g (20 mmol) of N-bromo succinimide(abbreviation: NBS) was added to this solution. After that, this mixturewas stirred for 27.5 hours. After the obtained suspension was washedwith water, moisture was removed by magnesium sulfate. This suspensionwas concentrated and dried to obtain 7.7 g of an objective white powderat a yield of 96%.

Step 3: Synthesis of 4-(1-naphthyl)-4′-phenyltriphenylamine

A synthetic scheme of 4-(1-naphthyl)-4′-phenyltriphenylamine in Step 3is shown in the following (L-3).

In a 100-mL three-neck flask, 8.0 g (20 mmol) of4-bromo-4′-phenyltriphenylamine, 3.4 g (20 mmol) of 1-naphthaleneboronicacid, 44 mg (0.2 mmol) of palladium(II) acetate, and 60 mg (0.4 mmol) oftri(o-tolyl)phosphine were put, and 20 mL of toluene, 10 mL of ethanol,and 15 mL of a potassium carbonate solution (2 mol/L) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, the mixture was stirred under a nitrogenatmosphere at 90° C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated, and methanolwas added thereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 8.6 g of an objective white powder at a yieldof 97%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.43 and that of 4-bromo-4′-phenyltriphenylamine was 0.50.

Step 4: Synthesis of 4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylamine

A synthetic scheme of 4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylaminein Step 4 is shown in the following (L-4).

After 8.6 g (19 mmol) of 4-(1-naphthyl)-4′-phenyltriphenylamine wasdissolved in 150 mL of ethyl acetate in a 300-mL conical flask, 3.4 g(19 mmol) of N-bromo succinimide (abbreviation: NBS) was added to thissolution. After that, this mixture was stirred at room temperature for24 hours. After completion of the reaction, this mixture solution waswashed with water, and magnesium sulfate was added thereto to removemoisture. This mixture solution was filtrated. The obtained filtrate wasconcentrated and purified by silica gel column chromatography(developing solvent, toluene:hexane=1:4). The obtained fraction wasconcentrated, and methanol was added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 8.1 g of an objectivewhite powder at a yield of 80%.

Step 5: Synthesis of4-(1-naphthyl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(Abbreviation: PCBBiNB)

A synthetic scheme of4-(1-naphthyl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine inStep 5 is shown in the following (L-5).

In a 50-mL three-neck flask, 1.6 g (3.0 mmol) of4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylamine, 0.9 g (30 mmol) of9-phenyl-9H-carbazol-3-yl-boronic acid, 12 mg (0.06 mmol) ofpalladium(II) acetate, and 36 mg (0.12 mmol) of tri(o-tolyl)phosphinewere put, and 15 mL of toluene, 15 mL of ethanol, and 3 mL of apotassium carbonate solution (2 mol/L) were added to this mixture. Thismixture was deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 2 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, acetone andmethanol were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 0.9 g of an objective white powder ata yield of 44%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.26 and that of 4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylamine was0.45.

A compound which was obtained through the above Step 5 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 49A and 49B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBBiNB (abbreviation) represented by the abovestructural formula (220), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.27-7.69 (m, 31H), 7.84 (d, J=7.8 Hz, 1H), 7.89-7.92 (m, 1H),8.04-8.08 (m, 1H), 8.18 (d, J=7.8 Hz, 1H), 8.36 (d, J=1.5 Hz, 1H).

In addition, an absorption spectrum of PCBBiNB (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 342 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 351 nm.

In addition, an emission spectrum of PCBBiNB (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 409 nm (excitationwavelength: 355 nm), and in the case of the thin film, a maximumemission wavelength was 433 nm (excitation wavelength: 336 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBBiNB (abbreviation) was −5.35 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.18 eV Thus, the energy gap in the solid statewas estimated to be 3.18 eV, which means that the LUMO level of PCBBiNB(abbreviation) is −2.17 eV.

An oxidation-reduction reaction characteristic of PCBBiNB (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBBiNB (abbreviation) was found to be=−5.42 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBBiNB (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 143° C.In this manner, PCBBiNB (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBBiNB(abbreviation) is a substance which is hard to be crystallized.

In addition, FIGS. 56 to 59 show the measurement results in elementcharacteristics of the light-emitting element 8 which was formed using,for a hole-transporting layer, PCBBiNB (abbreviation) which is thecarbazole derivative of the present invention that was synthesized inEmbodiment 10 in a manner similar to that of Embodiment 5. It was foundthat the hole-transporting material of the present invention which wasused for the light-emitting element 8 showed higher luminance, even whenthe hole-transporting material of the present invention which was usedfor the light-emitting element 8 was compared to NPB of thelight-emitting element 1. Note that the light-emitting element 1 whichis a comparative light-emitting element was formed using4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) forthe hole-transporting layer 151 in a manner similar to that ofEmbodiment 5.

In addition, in the light-emitting element 8, an emission wavelengthderived from PCBAPA which is a blue light-emitting material was observedbut an emission wavelength derived from the hole-transporting materialwas not observed from emission spectrum shown in FIG. 59. Thus, it wasfound that the hole-transporting material of the present inventionrealizes favorable carrier balance in the structure of thelight-emitting element 8.

FIG. 60 shows the result of a continuous lighting test in which thelight-emitting element 8 was continuously lit by constant currentdriving with the initial luminance set at 1000 cd/m² (the vertical axisindicates the relative luminance on the assumption that 1000 cd/m² is100%). From the results in FIG. 60, the light-emitting element 8 wasfound to have a longer lifetime, as compared to the light-emittingelement 1. Thus, a long lifetime light-emitting element can be obtainedby applying the present invention.

In addition, as another structure of the light-emitting element 8 shownin Embodiment 10, PCBBiNB (abbreviation) was used instead of NPB(abbreviation), which was used at the time of forming the first layer1511, and was co-evaporated with molybdenum(VI) oxide to form the firstlayer 1511. With the efficiency, the drive voltage at a luminance ofabout 1000 cd/m², and the reliability of such a light-emitting element8, favorable values equivalent to those of the light-emitting element 8were obtained. The light-emitting element 8 was formed in Embodiment 10by using a co-evaporation film of NPB and molybdenum(VI) oxide for ahole-injecting layer and using PCBBiNB (abbreviation) for ahole-transporting layer. When the drive voltage of the light-emittingelement 8 was 4.2 V, the luminance and the current value were 1062 cd/m²and 0.75 mA, respectively, and the light-emitting element 8 exhibited81% of the initial luminance when driven for 350 hours.

As thus described, it was found that PCBBiNB (abbreviation) was afavorable material which can be used for both the first layer 1511 whichis a hole-injecting layer and the second layer 1512 which is ahole-transporting layer at the same time. Accordingly, an element couldbe manufactured easily and material use efficiency could also beimproved.

Embodiment 11

In Embodiment 11, a synthetic method of a carbazole derivative of thepresent invention,

-   [4′-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)phenyl]amine    (abbreviation: PCBANT) represented by a structural formula (355),    will be specifically described.

Step 1: Synthesis of 4-(4-bromophenyl)-4′-phenyl-triphenylamine

A synthetic scheme of 4-(4-bromophenyl)-4′-phenyl-triphenylamine in Step1 is shown in the following (M−1).

In a 500-mL three-neck flask, 22 g (70 mmol) of 4,4′-dibromobiphenyl,8.5 g (50 mmol) of diphenylamine, 1.9 g (10 mmol) of copper(I) iodide,2.6 g (10 mmol) of 18-crown-6-ether, 6.9 g (50 mmol) of potassiumcarbonate, and 50 mL of1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviation: DMPU)were put, and the mixture was stirred under a nitrogen atmosphere at180° C. for 37 hours.

After the reaction, 500 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, and hexaneand methanol were added thereto. The mixture was irradiated withsupersonic and then recrystallized to obtain 5.3 g of an objective whitepowder at a yield of 27%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.5 and that of 4,4′-dibromobiphenyl was 0.59.

Step 2: Synthesis of [4′-(1-naphthyl)biphenyl-4-yl]diphenylamine

A synthetic scheme of [4′-(1-naphthyl)biphenyl-4-yl]diphenylamine inStep 2 is shown in the following (M−2).

In a 100-mL three-neck flask, 4.0 g (10 mmol) of4-(4-bromophenyl)-4′-phenyl-triphenylamine, 1.7 g (10 mmol) of1-naphthaleneboronic acid, 11 mg (0.05 mmol) of palladium(II) acetate,and 15 mg (0.05 mmol) of tri(o-tolyl)phosphine were put, and 20 mL oftoluene, 5 mL of ethanol, and 10 mL of a potassium carbonate solution (2mol/L) were added to this mixture. This mixture was deaerated whilebeing stirred under low pressure. After the deaeration, the mixture wasstirred under a nitrogen atmosphere at 90° C. for 7 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through silica gel, alumina,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through silica gel, alumina, and then Celite to obtainfiltrate. The obtained filtrate was concentrated, and methanol was addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 3.6 g of an objective white powder at a yieldof 80%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.58 and that of 4-bromophenyl-4′-phenyl-triphenylamine was 0.65.

Step 3: Synthesis of(4-bromophenyl)[4′-(1-naphthyl)biphenyl-4-yl]phenylamine

A synthetic scheme of(4-bromophenyl)[4′-(1-naphthyl)biphenyl-4-yl]phenylamine in Step 3 isshown in the following (M-3).

After 3.6 g (8.0 mmol) of [4′-(1-naphthyl)biphenyl-4-yl]diphenylaminewas dissolved in 100 mL of ethyl acetate in a 200-mL conical flask, 1.4g (8.0 mmol) of N-bromo succinimide (abbreviation: NBS) was added tothis solution. After that, this mixture was stirred at room temperaturefor 72 hours. After completion of the reaction, this mixture solutionwas washed with water, and magnesium sulfate was added thereto to removemoisture. This mixture solution was filtrated, the obtained filtrate wasconcentrated, and methanol was added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 3.9 g of an objectivewhite powder at a yield of 93%.

Step 4: Synthesis of[4′-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)phenyl]amine(Abbreviation: PCBANT)

A synthetic scheme of[4′-(1-naphthyl)biphenyl-4-yl](phenyl)[4-(9-phenyl-9H-carbazol-3-yl)phenyl]aminein Step 4 is shown in the following (M-4).

In a 100-mL three-neck flask, 1.6 g (3 mmol) of(4-bromophenyl)[4′-(1-naphthyl)biphenyl-4-yl]phenylamine, 0.8 g (3 mmol)of 9-phenyl-9H-carbazol-3-boronic acid, 6.0 mg (0.03 mmol) ofpalladium(II) acetate, and 18 mg (0.03 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, 5 mL of ethanol, and 3 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 80°C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, and then Celite to obtain filtrate.The obtained filtrate was concentrated and purified by silica gel columnchromatography (developing solvent, toluene:hexane=1:4). The obtainedfraction was concentrated, and methanol was added thereto. The mixturewas irradiated with supersonic and then recrystallized to obtain 1.2 gof an objective white powder at a yield of 60%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.28 and that of(4-bromophenyl)[4′-(1-naphthyl)biphenyl-4-yl]phenylamine was 0.42.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 50A and 50B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBANT (abbreviation) represented by the abovestructural formula (355), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.08 (t, J=7.5 Hz, 1H), 7.20-7.73 (m, 30H), 7.87 (d, J=8.1 Hz,1H), 7.92 (d, J=7.2 Hz, 1H), 8.00 (d, J=8.4 Hz, 1H), 8.19 (d, J=7.8 Hz,1H), 8.35 (d, J=1.8 Hz, 1H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the formic acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 689.30 (mode is ES+) was detected, and it wasconfirmed that an objective PCBANT (abbreviation) was obtained.

In addition, an absorption spectrum of PCBANT (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 342 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 351 nm.

In addition, an emission spectrum of PCBANT (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 414 nm (excitationwavelength: 355 nm), and in the case of the thin film, a maximumemission wavelength was 342 nm (excitation wavelength: 365 nm). Sincethe measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBANT (abbreviation) was −5.38 eV. TheTauc plot of the absorption spectrum of the thin film revealed that theabsorption edge was 3.11 eV. Thus, the energy gap in the solid state wasestimated to be 3.11 eV, which means that the LUMO level of PCBANT(abbreviation) is −2.27 eV.

An oxidation-reduction reaction characteristic of PCBANT (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBANT (abbreviation) was found to be=−5.43 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBANT (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 131° C.In this manner, PCBANT (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBANT(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBANT (abbreviation) which was synthesized in Embodiment 11 in a mannersimilar to that of Embodiment 5 for a hole-transporting layer, favorablevalues equivalent to those of the light-emitting element 8 which wasformed using PCBBiNB in Embodiment 10 were obtained. When the drivevoltage of the light-emitting element was 4.0 V, the luminance and thecurrent value were 1186 cd/m² and 0.73 mA, respectively, and thelight-emitting element exhibited 65% of the initial luminance whendriven for 180 hours.

Embodiment 12

In Embodiment 12, a synthetic method of a carbazole derivative of thepresent invention,4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-phenyl-triphenylamine(abbreviation: BCBA1BP) represented by a structural formula (63), willbe specifically described.

Step 1: Synthesis of 9-(biphenyl-4-yl)-9H-carbazole

A synthetic scheme of 9-(biphenyl-4-yl)-9H-carbazole in Step 1 is shownin the following (N-1).

In a 200-mL three-neck flask, 12 g. (50 mmol) of 4-bromobiphenyl, 8.4 g(50 mmol) of carbazole, 230 mg (1 mmol) of palladium acetate(abbreviation: Pd(OAc)(II)), 1.8 g (3.0 mmol) of1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF), and 13 g (180mmol) of sodium tert-butoxide were put, and the atmosphere of the flaskwas substituted by nitrogen. Then, 80 mL of dehydrated xylene was addedto this mixture. This mixture was deaerated while being stirred underlow pressure, and the mixture was stirred under a nitrogen atmosphere at120° C. for 7.5 hours to be reacted.

After completion of the reaction, about 600 mL of heated toluene wasadded to this suspension, and filtrated twice through Florisil, alumina,and then Celite. The obtained filtrate was concentrated, and hexane wasadded thereto. The mixture was recrystallized to obtain 14 g of anobjective white powder at a yield of 87%.

Step 2: Synthesis of 9-(biphenyl-4-yl)-3-bromo-9H-carbazole

A synthetic scheme of 9-(biphenyl-4-yl)-3-bromo-9H-carbazole in Step 2is shown in the following (N-2).

After 3.1 g (10 mmol) of 9-(biphenyl-4-yl)-9H-carbazole was dissolved in100 mL of chloroform in a 200-mL conical flask, 1.8 g (10 mmol) ofN-bromo succinimide (abbreviation: NBS) was added to this solution.After that, this mixture was stirred at room temperature for 24 hours.After completion of the reaction, this mixture solution was washed withwater, and magnesium sulfate was added thereto to remove moisture. Thismixture solution was filtrated, and the obtained filtrate wasconcentrated and dried to obtain 3.7 g of an objective white powder at ayield of 95%.

Step 3: Synthesis of [9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic Acid

A synthetic scheme of [9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acidin Step 3 is shown in the following (N-3).

In a 500-mL three-neck flask, 8.0 g (20 mmol) of9-(4-biphenyl)-3-bromo-9H-carbazole was put, and the atmosphere in theflask was substituted by nitrogen. Then, 200 mL of tetrahydrofuran(abbreviation: THF) was added thereto to reach −78° C. After that, 16 mL(24 mmol) of an n-butyllithium hexane solution (1.6 mol/L) was droppedonto this mixture solution, and the solution was stirred for 2 hours.Then, 4.0 mL (40 mmol) of trimethyl borate was added to this reactionmixture, and the mixture was stirred at −78° C. for 2 hours and at roomtemperature for 18 hours. After the reaction, 50 mL of 1M dilutehydrochloric acid was added to this reaction solution, and the mixturewas stirred for 3 hours. This mixture was extracted with toluene, andthe obtained organic layer was washed with a saturated saline solution.After the washing, magnesium sulfate was added to the organic layer toremove moisture. This suspension was filtrated, the obtained filtratewas concentrated, and hexane was added thereto. The mixture wasirradiated with supersonic and then recrystallized to obtain 6.6 g of anobjective white powder at a yield of 91%.

Step 4: Synthesis of4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-phenyl-triphenylamine(Abbreviation: BCBA1BP)

A synthetic scheme of4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-phenyl-triphenylamine in Step4 is shown in the following (N-4).

In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of4-bromo-4′-phenyl-triphenylamine, 1.1 g (3.0 mmol) of[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.03 mmol) ofpalladium(II) acetate, and 18 mg (0.06 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, mL of ethanol, and 3 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil, alumina, silica gel, and then Celite to obtainfiltrate. The obtained filtrate was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 1.5 g of an objective white powder ata yield of 79%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.45 and that of 4-bromo-4′-phenyl-triphenylamine was 0.68.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 51A and 51B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, BCBA1BP (abbreviation) represented by the abovestructural formula (63), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.06 (t, J=7.2 Hz, 1H), 7.20-7.72 (m, 29H), 7.83 (d, J=8.4 Hz,2H), 8.19 (d, J=7.8 Hz, 1H), 8.35 (s, 1H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the formic acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 638.27 (mode is ES+) was detected, and it wasconfirmed that an objective BCBA1BP (abbreviation) was obtained.

In addition, an absorption spectrum of PCBA1BP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 336 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 342 nm.

In addition, an emission spectrum of PCBA1BP (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 394 nm (excitationwavelength: 350 nm), and in the case of the thin film, a maximumemission wavelength was 408 nm (excitation wavelength: 301 nm). Sincethe measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBA1BP (abbreviation) was −5.48 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.19 eV. Thus, the energy gap in the solid statewas estimated to be 3.19 eV, which means that the LUMO level of PCBA1BP(abbreviation) is −2.29 eV.

An oxidation-reduction reaction characteristic of PCBA1BP (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of PCBA1BP (abbreviation) was found to be=−5.43 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBA1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 122° C.In this manner, PCBA1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBA1BP(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBA1BP (abbreviation) which was synthesized in Embodiment 12 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.0 V, the luminance andthe current value were 1031 cd/m² and 0.72 mA, respectively, and thelight-emitting element exhibited 89% of the initial luminance whendriven for 180 hours.

Embodiment 13

In Embodiment 13, a synthetic method of a carbazole derivative of thepresent invention,4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-(1-naphthyl)triphenylamine(abbreviation: BCBANB) represented by a structural formula (364), willbe specifically described.

Step 1: Synthesis of 4-bromotriphenylamine

A synthetic scheme of 4-bromotriphenylamine in Step 1 is shown in thefollowing (O-1).

To 1.5 L of an ethyl acetate solution containing 54.0 g (220 mmol) oftriphenylamine, 35.6 g (200 mmol) of N-bromo succinimide (abbreviation:NBS) was added. Then, the mixture was stirred for 24 hours. After theobtained suspension was concentrated to 1 L, the concentrated suspensionwas washed with 1 L of an aqueous solution containing 5% of sodiumacetate. After the washing, this solution was further concentrated toabout 50 mL. Then, methanol was added to the concentrated solution andthe solution was precipitated. The obtained precipitate was filtered anddried to obtain 46.5 g of an objective white powder at a yield of 73%.

Step 2: Synthesis of 4-(1-naphthyl)triphenylamine

A synthetic scheme of 4-(1-naphthyl)triphenylamine in Step 2 is shown inthe following (0-2).

In a 20 mL three-neck flask, 9.7 g (30 mmol) of 4-bromotriphenylamine,5.7 g (33 mmol) of 1-naphthaleneboronic acid, 67 mg (0.3 mmol) ofpalladium(II) acetate, and 91 g (0.3 mmol) of tri(o-tolyl)phosphine wereput, and 20 mL of toluene, 20 mL of ethanol, and 20 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 2 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with sodium hydrogencarbonate solution and water in this order, and magnesium sulfate wasadded thereto to dry the filtrate. After the drying, this suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and dried toobtain 11 g of an objective light-yellow solid at a yield of 99%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.48 and that of 4-bromotriphenylamine was 0.55.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). It was found from themeasurement result that the compound of the present inventionrepresented by the above structural formula (364) was obtained. ¹H NMR(CDCl₃, 300 MHz): δ (ppm)=7.07 (t, J=7.5 Hz, 1H), 7.22-7.61 (m, 21H),7.83 (d, J=7.8 Hz, 1H), 7.88-7.91 (m, 1H), 8.02-8.05 (m, 1H).

Step 3: Synthesis of 4-bromo-4′-(1-naphthyl)triphenylamine

A synthetic scheme of 4-bromo-4′-(1-naphthyl)triphenylamine in Step 3 isshown in the following (0-3).

After 11 g (30 mmol) of 4-(1-naphthyl)triphenylamine was dissolved in300 mL of ethyl acetate in a 500-mL recovery flask, 5.3 g (30 mmol) ofN-bromo succinimide (abbreviation: NBS) was added to this solution.After that, this mixture was stirred at room temperature for 168 hours.After completion of the reaction, this mixture solution was washed withwater, and magnesium sulfate was added thereto to remove moisture. Thismixture solution was filtrated, and the obtained filtrate wasconcentrated and purified by silica gel column chromatography(developing solvent, toluene:hexane=1:4). The obtained fraction wasconcentrated, and methanol was added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 7.8 g of an objectivewhite powder at a yield of 43%.

Step 4: Synthesis of4-[9-(biphenyl-4-yl)-9H-carabazol-3-yl]-4′-(1-naphthyl)triphenylamine(Abbreviation: BCBANB)

A synthetic scheme of4-[9-(biphenyl-4-yl)-9H-carabazol-3-yl]-4′-(1-naphthyl)triphenylamine inStep 4 is shown in the following (0-4).

In a 100-mL three-neck flask, 1.35 g (3.0 mmol) of4-bromo-4′-(1-naphthyl)triphenylamine, 1.1 g (3.0 mmol) of[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.02 mmol) ofpalladium(II) acetate, and 9.0 mg (0.06 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, 5 mL of ethanol, and 3 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 3 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, and acetoneand methanol were added thereto. The mixture was irradiated withsupersonic and then recrystallized to obtain 1.0 g of an objective whitepowder at a yield of 50%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.45 and that of 4-bromo-4′-(1-naphthyl)triphenylamine was 0.66.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 52A and 52B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, BCBANB (abbreviation) represented by the abovestructural formula (364), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.08 (t, J=6.9 Hz, 1H), 7.28-7.71 (m, 28H), 7.82-7.86 (m, 3H),7.89-7.92 (m, 1H), 8.04-8.07 (m, 1H), 8.20 (d, J=7.8 Hz, 1H), 8.37 (d,J=1.2 Hz, 1H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the forminc acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 556.52 (mode is ES+) was detected, and it wasconfirmed that an objective BCBANB (abbreviation) was obtained.

In addition, an absorption spectrum of BCBANB (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 335 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 344 nm.

In addition, an emission spectrum of BCBANB (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 410 nm (excitationwavelength: 345 nm), and in the case of the thin film, a maximumemission wavelength was 422 nm (excitation wavelength: 328 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of BCBANB (abbreviation) was −5.42 eV. TheTauc plot of the absorption spectrum of the thin film revealed that theabsorption edge was 3.19 eV. Thus, the energy gap in the solid state wasestimated to be 3.19 eV, which means that the LUMO level of BCBANB(abbreviation) is −2.23 eV

An oxidation-reduction reaction characteristic of BCBANB (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of BCBANB (abbreviation) was found to be=−5.45 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of BCBANB (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 130° C.In this manner, BCBANB (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that BCBANB(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingBCBANB (abbreviation) which was synthesized in Embodiment 13 in a mannersimilar to that of Embodiment 5 for a hole-transporting layer, favorablevalues equivalent to those of the light-emitting element 8 which wasformed using PCBBiNB in Embodiment 10 were obtained. When the drivevoltage of the light-emitting element was 4.0 V, the luminance and thecurrent value were 848 cd/m² and 0.52 mA, respectively.

Embodiment 14

In Embodiment 14, a synthetic method of a carbazole derivative of thepresent invention,4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-(1-naphthyl)₄″-phenyl-triphenylamine(abbreviation: BCBBiNB) represented by a structural formula (366), willbe specifically described.

Step 1: Synthesis of4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-(1-naphthyl)-4″-phenyl-triphenylamine(Abbreviation: BCBBiNB)

A synthetic scheme of4-[9-(biphenyl-4-yl)-9H-carbazol-3-yl)-4′-(1-naphthyl)₄″-phenyl-triphenylaminein Step 1 is shown in the following (P-1).

In a 100-mL three-neck flask, 1.6 g (3.0 mmol) of4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylamine, 1.1 g (3.0 mmol) of[9-(biphenyl-4-yl)-9H-carbazol-3-yl]boronic acid, 6.0 mg (0.03 mmol) ofpalladium(II) acetate, and 18 mg (0.03 mmol) of tri(o-tolyl)phosphinewere put, and 20 mL of toluene, mL of ethanol, and 3 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, and acetoneand methanol were added thereto. The mixture was irradiated withsupersonic and then recrystallized to obtain 1.4 g of an objective whitepowder at a yield of 60%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.26 and that of 4-bromo-4′-(1-naphthyl)-4″-phenyl-triphenylamine was0.46.

A compound which was obtained through the above Step 1 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 53A and 53B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, BCBBiNB (abbreviation) represented by the abovestructural formula (366), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.30-7.71 (m, 33H), 7.82-7.86 (m, 3H), 7.90-7.93 (m, 1H),8.05-8.08 (m, 1H), 8.20 (d, J=7.8 Hz, 1H), 8.38 (d, J=1.5 Hz, 1H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the forminc acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 765.32 (mode is ES+) was detected, and it wasconfirmed that an objective BCBBiNB (abbreviation) was obtained.

In addition, an absorption spectrum of BCBBiNB (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 342 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 351 nm.

In addition, an emission spectrum of BCBBiNB (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 409 nm (excitationwavelength: 355 nm), and in the case of the thin film, a maximumemission wavelength was 433 nm (excitation wavelength: 336 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of BCBBiNB (abbreviation) was −5.35 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.18 eV Thus, the energy gap in the solid statewas estimated to be 3.18 eV, which means that the LUMO level of BCBBiNB(abbreviation) is −2.17 eV.

An oxidation-reduction reaction characteristic of BCBBiNB (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of BCBBiNB (abbreviation) was found to be=−5.42 [eV]. In addition,the oxidation peak took a similar value even after the 100 cycles.Accordingly, it was found that repetition of the oxidation reductionbetween an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of BCBBiNB (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 143° C.In this manner, BCBBiNB (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that BCBBiNB(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingBCBBiNB (abbreviation) which was synthesized in Embodiment 14 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.0 V, the luminance andthe current value were 996 cd/m² and 0.59 mA, respectively, and thelight-emitting element exhibited 84% of the initial luminance whendriven for 180 hours.

Embodiment 15

In Embodiment 15, a synthetic method of a carbazole derivative of thepresent invention,4-{9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4′-phenyl-triphenylamine(abbreviation: NBCBA1BP) represented by a structural formula (386), willbe specifically described.

Step 1: Synthesis of 9-(4-bromophenyl)-9H-carbazole

A synthetic scheme of 9-(4-bromophenyl)-9H-carbazole in Step 1 is shownin the following (Q-1).

In a 300-mL three-neck flask, 56 g (240 mmol) of 1,4-dibromobenzene, 31g (180 mmol) of 9H-carabazole, 4.6 g (24 mmol) of copper(I) iodide, 2.1g (8.0 mmol) of 18-crown-6-ether, 66 g (480 mmol) of potassiumcarbonate, and 8 mL of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone(abbreviation: DMPU) were put, and the mixture was stirred under anitrogen atmosphere at 180° C. for 6 hours.

After the reaction, this suspension was filtrated, and the filtrate waswashed with dilute hydrochloric acid, a saturated sodium hydrogencarbonate solution, and a saturated saline solution in this order. Then,moisture was removed by magnesium sulfate. This suspension wasfiltrated, and the obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=9:1). The obtained fraction was concentrated, andchloroform and hexane were added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 21 g of an objectivelight brown plate-like crystal at a yield of 35%.

Step 2: Synthesis of 9-[4-(1-naphthyl)phenyl]-9H-carbazole

A synthetic scheme of 9-[4-(1-naphthyl)phenyl]-9H-carbazole in Step 2 isshown in the following (Q-2).

In a 100-mL three-neck flask, 4.8 g (15 mmol) of9-(4-bromophenyl)-9H-carbazole, 2.6 g (15 mmol) of 1-naphthaleneboronicacid, 2.0 mg (0.01 mmol) of palladium(II) acetate, and 6.0 mg (0.02mmol) of tri(o-tolyl)phosphine were put, and 20 mL of toluene, 10 mL ofethanol, and 10 mL of a potassium carbonate solution (2 mol/L) wereadded to this mixture. This mixture was deaerated while being stirredunder low pressure. After the deaeration, the mixture was stirred undera nitrogen atmosphere at 90° C. for 9 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil, alumina, silica gel, and then Celite to obtainfiltrate. The obtained filtrate was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 5.0 g of an objective white powder ata yield of 90%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.46 and that of 9-(4-bromophenyl)-9H-carbazole was 0.54.

Step 3: Synthesis of 3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole

A synthetic scheme of 3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole inStep 3 is shown in the following (Q-3).

After 5.0 g (14 mmol) of 9-[4-(1-naphthyl)phenyl]-9H-carbazole wasdissolved in a mixture solvent of 50 mL of toluene and 250 mL of ethylacetate in a 300-mL conical flask, 2.5 g (14 mmol) of N-bromosuccinimide (abbreviation: NBS) was added to this solution. After that,this mixture was stirred at room temperature for 168 hours. Aftercompletion of the reaction, this mixture solution was filtrated throughFlorisil and then Celite. Then, the obtained filtrate was washed withwater, and magnesium sulfate was added thereto to remove moisture. Thismixture solution was filtrated, the obtained filtrate was concentrated,and hexane was added thereto. Then, the mixture was irradiated withsupersonic to obtain 6.1 g of an objective white powder at a yield of99%.

Step 4: Synthesis of 9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronic acid

A synthetic scheme of 9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronicacid in Step 4 is shown in the following (Q-4).

In a 500-mL three-neck flask, 5.0 g (14 mmol) of3-bromo-9-[4-(1-naphthyl)phenyl]-9H-carbazole was put, and theatmosphere in the flask was substituted by nitrogen. Then, 200 mL oftetrahydrofuran (abbreviation: THF) was added thereto to reach −78° C.11 mL (17 mmol) of an n-butyllithium hexane solution (1.6 mol/L) wasdropped onto this mixture solution, and the solution was stirred for 4hours. After that, 2.7 mL (27 mmol) of trimethyl borate was added tothis reaction mixture, and the mixture was stirred at −78° C. for 2hours and at room temperature for 16 hours. After the reaction, 50 mL of1M dilute hydrochloric acid was added to this reaction solution, and themixture was stirred for 4 hours. This mixture was extracted withtoluene, and the obtained organic layer was washed with a saturatedsaline solution. After the washing, magnesium sulfate was added to theorganic layer to remove moisture. This suspension was filtrated, theobtained filtrate was concentrated, and chloroform and hexane were addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 3.5 g of an objective white powder at a yieldof 63%.

Step 5: Synthesis of4-{9-[4(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4′-phenyl-triphenylamine(Abbreviation: NBCBA1BP)

A synthetic scheme of4-{9-[4(1-naphthyl)phenyl]-9H-carbazol-3-yl}-4′-phenyl-triphenylamine inStep 5 is shown in the following (Q-5).

In a 50-mL three-neck flask, 1.0 g (2.5 mmol) of4-bromo-4′-phenyl-triphenylamine, 1.0 g (2.5 mmol) of9-[4-(1-naphthyl)phenyl]-9H-carbazol-3-boronic acid, 4.0 mg (0.02 mmol)of palladium(II) acetate, and 6.0 mg (0.02 mmol) oftri(o-tolyl)phosphine were put, and 20 mL of toluene, 5 mL of ethanol,and 2.5 mL of a potassium carbonate solution (2 mol/L) were added tothis mixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, the mixture was stirred under a nitrogenatmosphere at 90° C. for 13 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 1.2 g of an objective white powder ata yield of 70%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.41 and that of 4-bromo-4′-phenyl-triphenylamine was 0.62.

A compound which was obtained through the above Step 5 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 54A and 54B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, NBCBA1BP (abbreviation) represented by the abovestructural formula (386), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.06 (t, J=6.6 Hz, 1H), 7.21-7.77 (m, 30H), 7.92-7.98 (m, 2H),8.04-8.08 (m, 1H), 8.22 (d, J=7.8 Hz, 1H), 8.37 (d, J=1.5 Hz, 1H).

In addition, an absorption spectrum of NBCBA1BP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 333 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 340 nm.

In addition, an emission spectrum of NBCBA1BP (abbreviation)(measurement range: 370 nm to 550 nm) was measured. In the case of thetoluene solution, a maximum emission wavelength was 393 nm (excitationwavelength: 350 nm), and in the case of the thin film, a maximumemission wavelength was 488 nm (excitation wavelength: 302 nm).

Since the measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of NBCBA1BP (abbreviation) was −5.53 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.22 eV. Thus, the energy gap in the solid statewas estimated to be 3.22 eV, which means that the LUMO level of NBCBA1BP(abbreviation) is −2.31 eV.

An oxidation-reduction reaction characteristic of NBCBA1BP(abbreviation) was examined by a cyclic voltammetry (CV) measurement.Since the measurement method is similar to that of Embodiment 1, thedescription is omitted.

According to the calculation similar to that of Embodiment 1, the HOMOlevel of NBCBA1BP (abbreviation) was found to be=−5.43 [eV]. Inaddition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of NBCBA1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 132° C.In this manner, NBCBA1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that NBCBA1BP(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingNBCBA1BP (abbreviation) which was synthesized in Embodiment 15 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 3.6 V, the luminance andthe current value were 773 cd/m² and 0.47 mA, respectively.

Embodiment 16

In Embodiment 16, a synthetic method of a carbazole derivative of thepresent invention,4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4′-phenyl-triphenylamine(abbreviation: NCBA1BP) represented by a structural formula (395), willbe specifically described.

Step 1: Synthesis of 9-(1-naphthyl)-9H-carbazole

A synthetic scheme of 9-(1-naphthyl)-9H-carbazole in Step 1 is shown inthe following (R-1).

In a 500-mL three-neck flask, 21 g (100 mmol) of 1-bromonaphthalene, 17g (100 mmol) of carabazole, 0.1 g (5.0 mmol) of copper(I) iodide, 0.7 g(2.5 mmol) of 18-crown-6-ether, 33 g (240 mmol) of potassium carbonate,and 80 mL of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone(abbreviation: DMPU) were put, and the mixture was stirred under anitrogen atmosphere at 170° C. for 6 hours. Then, 10 g (50 mmol) of1-bromonaphthalene, 2.0 g (10 mmol) of copper(I) iodide, and 2.6 g (10mmol) of 18-crown-6-ether were further added to this reaction mixture,and the mixture was further stirred at 170° C. for 7.5 hours. Afterthat, 10 g (50 mmol) of 1-bromonaphthalene was further added to thisreaction mixture, and the mixture was further stirred at 180° C. for 6hours.

After the reaction, about 200 mL of toluene and about 100 mL ofhydrochloric acid (1 mol/L) were added to this reaction mixture, and themixture was filtered through Celite. The obtained filtrate was filtratedthrough Florisil and Celite. The obtained filtrate was separated into anorganic layer and an aqueous layer. After this organic layer was washedwith hydrochloric acid (1 mol/L) and water in this order, magnesiumsulfate was added to remove moisture. This suspension was filteredthrough Florisil and Celite. Then, hexane was added to the oilysubstance obtained by concentrating the obtained filtrate, and themixture was irradiated with supersonic and then recrystallized to obtain22 g of an objective white powder at a yield of 75%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.61, that of 1-bromonaphthalene was 0.74, and that of carbazole was0.24.

Step 2: Synthesis of 3-bromo-9-(1-naphthyl)-9H-carbazole

A synthetic scheme of 3-bromo-9-(1-naphthyl)-9H-carbazole in Step 2 isshown in the following (R-2).

After 5.9 g (20 mmol) of 9-(1-naphthyl)-9H-carbazole was dissolved in amixture solvent of 50 mL of toluene and 50 mL of ethyl acetate in a500-mL conical flask, 3.6 g (20 mmol) of N-bromo succinimide(abbreviation: NBS) was added to this solution. After that, this mixturewas stirred at room temperature for 170 hours. After completion of thereaction, this mixture solution was washed with water, and magnesiumsulfate was added thereto to remove moisture. This mixture solution wasfiltrated, and the obtained filtrate was concentrated and dried toobtain 7.4 g of an objective white powder at a yield of 99%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.43 and that of 9-(1-naphthyl)₉H-carbazole was 0.35.

Step 3: Synthesis of 9-(1-naphthyl)9H-carbazol-3-boronic Acid

A synthetic scheme of 9-(1-naphthyl)9H-carbazol-3-boronic acid in Step 3is shown in the following (R-3).

In a 500-mL three-neck flask, 3.7 g (10 mmol) of9-(1-naphthyl)9H-carbazole was put, and the atmosphere in the flask wassubstituted by nitrogen. Then, 200 mL of tetrahydrofuran (abbreviation:THF) was added thereto, and the mixture was stirred at −78° C. Then, 7mL (13 mmol) of an n-butyllithium hexane solution (1.6 mol/L) wasdropped onto this mixture solution, and the solution was stirred for 2hours. After that, 2 mL (20 mmol) of trimethyl borate was added to thisreaction mixture, and the mixture was stirred at −78° C. for 3 hours andat room temperature for 16 hours. After the reaction, 50 mL of 1M dilutehydrochloric acid wes added to this reaction solution, and the mixturewas stirred for 4 hours. This mixture was extracted with ethyl acetate,and the obtained organic layer was washed with a saturated salinesolution. After the washing, magnesium sulfate was added to the organiclayer to remove moisture. This suspension was filtrated, the obtainedfiltrate was concentrated, and chloroform and hexane were added thereto.The mixture was irradiated with supersonic and then recrystallized toobtain 2.6 g of an objective yellow powder at a yield of 78%.

Step 4: Synthesis of4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4′-phenyl-triphenylamineAbbreviation: NCBA1BP)

A synthetic scheme of4-[9-(1-naphthyl)-9H-carbazol-3-yl]-4′-phenyl-triphenylamine(abbreviation: NCBA1BP) in Step 4 is shown in the following (R-4).

In a 50-mL three-neck flask, 1.2 g (3.0 mmol) of4-bromo-4′-phenyl-triphenylamine, 1.0 g (3.0 mmol) of9-(1-naphthyl)9H-carbazol-3-boronic acid, 6.0 mg (0.03 mmol) ofpalladium(II) acetate, and 0.03 mg (18 mmol) of tri(o-tolyl)phosphinewere put, and 15 mL of toluene, 5 mL of ethanol, and 3 mL of a potassiumcarbonate solution (2 mol/L) were added to this mixture. This mixturewas deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 6.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:3). The obtained fraction was concentrated, andmethanol was added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 0.5 g of an objective white powder ata yield of 25%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.34 and that of 4-bromo-4′-phenyl-triphenylamine was 0.54.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 55A and 55B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, NCBA1BP (abbreviation) represented by the abovestructural formula (395), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.00-7.07 (m, 3H), 7.19-8.00 (m, 25H), 8.03-8.07 (m, 2H),8.22-8.25 (m, 1H), 8.40 (d, J=1.5, 1H).

In addition, an absorption spectrum of NCBA1BP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 333 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 340 nm.

In addition, an emission spectrum of NCBA1BP (abbreviation) (measurementrange: 370 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 392 nm (excitationwavelength: 345 nm), and in the case of the thin film, a maximumemission wavelength was 426 nm (excitation wavelength: 328 nm). Sincethe measurement method of an absorption spectrum and an emissionspectrum is similar to that of Embodiment 1, the description is omitted.

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of NCBA1BP (abbreviation) was −5.44 eV TheTauc plot of the absorption spectrum of the thin film revealed that theabsorption edge was 3.19 eV. Thus, the energy gap in the solid state wasestimated to be 3.19 eV, which means that the LUMO level of NCBA1BP(abbreviation) is −2.25 eV.

An oxidation-reduction reaction characteristic of NCBA1BP (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted. According to the calculation similar to that of Embodiment1, the HOMO level of NCBA1BP (abbreviation) was found to be=−5.43 [eV].In addition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of NCBA1BP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 128° C.In this manner, NCBA1BP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that NCBA1BP(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingNCBA1BP (abbreviation) which was synthesized in Embodiment 16 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.0 V, the luminance andthe current value were 1198 cd/m² and 0.82 mA, respectively.

Embodiment 17

In Embodiment 17, a synthetic method of a carbazole derivative of thepresent invention,4,4′-diphenyl-4″-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BPIII) represented by a structural formula (422),will be specifically described.

Step 1: Synthesis of 3-bromo-6,9-diphenyl-9H-carbazole

A synthetic scheme of 3-bromo-6,9-diphenyl-9H-carbazole in Step 1 isshown in the following (S-1).

In a 300-mL erlenmayer flask, 4.8 g (15 mmol) of3,9-diphenyl-9H-carbazole was put, and 250 mL of a mixture solvent(ethyl acetate: toluene=4:1) was added to this solution. After that,this mixture was stirred for 30 minutes. Then, 2.7 g (15 mmol) ofN-bromo succinimide (abbreviation: NBS) was added to this solutionlittle by little, and the solution was stirred for 48 hours.

After the stirring, this mixture was washed with a saturated sodiumhydrogen carbonate solution and a saturated saline solution in thisorder. After the washing, moisture of the obtained organic layer wasremoved by magnesium sulfate. Then, suction filtration was performed onthis mixture and the magnesium sulfate was removed to obtain filtrate. Asmall amount of ethanol was added to an oily substance which wasobtained by concentrating the obtained filtrate. Then, the mixture wasirradiated with supersonic to precipitate a solid. The precipitatedsolid was collected by suction filtration to obtain 5.4 g of a whitepowder-like solid at a yield of 90%.

Step 2: Synthesis of4,4′-diphenyl-4″-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine(Abbreviation: PCBBi1BPIII)

A synthetic scheme of4,4′-diphenyl-4″-(6,9-diphenyl-9H-carbazol-3-yl)triphenylamine in Step 2is shown in the following (S-2).

In a 100-mL three-neck flask, 1.7 g (3.8 mmol) ofN,N-bis(biphenyl-4-yl)aminophenyl-4-boronic acid, 1.5 g (3.8 mmol) of3-bromo-6,9-diphenyl-9H-carbazole, 8.4 mg (0.038 mmol) of palladium(II)acetate, and 0.080 mg (0.26 mmol) of tri(o-tolyl)phosphine were put.Then, 10 mL of toluene, 2 mL of ethanol, and 10 mL of a 2M potassiumcarbonate solution were added to this mixture. After this mixture wasdeaerated under low pressure, the atmosphere in the flask wassubstituted by nitrogen. This mixture was stirred at 100° C. for 3hours.

After the stirring, toluene was added to this reaction mixture, and thismixture was heated at 50° C. and stirred. After this suspension wasbrought back to room temperature, the suspension was separated into anorganic layer and an aqueous layer. The obtained organic layer waswashed with a saturated sodium carbonate solution and a saturated salinesolution in this order. After the washing, magnesium sulfate was addedto the obtained organic layer to remove moisture. Suction filtration wasperformed on this mixture to obtain filtrate. Suction filtration wasperformed on the obtained filtrate through Celite (Wako Pure ChemicalIndustries, Ltd., catalog No.: 531-16855), Florisil (Wako Pure ChemicalIndustries, Ltd., catalog No.: 540-00135), and alumina to obtainfiltrate. The obtained filtrate was concentrated and purified by silicagel column chromatography. The silica gel column chromatography wasperformed by, first, using a mixture solvent of toluene:hexane=1:4 as adeveloping solvent, and then using a mixture solvent oftoluene:hexane=1:1 as another developing solvent. A solid which wasobtained by concentrating the obtained fraction was recrystallized witha mixture solvent of chloroform and hexane to obtain 2.3 g of a whitepowder-like solid at a yield of 87%.

Sublimation purification of 2.3 g of the obtained white solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa, with a flow rate ofargon at 4 mL/min, at 320° C. for 18 hours to obtain 1.8 g of the whitesolid at a yield of 78%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 61A and 61B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBBi1BPIII (abbreviation) represented by theabove structural formula (422), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.22-7.77 (m, 36H), 8.38-8.42 (m, 2H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the forminc acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 714.30 (mode is ES+) was detected, and it wasconfirmed that an objective PCBBi1BPIII (abbreviation) was obtained.

In addition, various physical properties of PCBBi1BPIII (abbreviation)were measured as described below.

In addition, an absorption spectrum of PCBBi1BPIII (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 348 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 352 nm.In addition, an emission spectrum of PCBBi1BPIII (abbreviation)(measurement range: 390 nm to 550 nm) was measured. In the case of thetoluene solution, a maximum emission wavelength was 397 nm (excitationwavelength: 358 nm), and in the case of the thin film, a maximumemission wavelength was 439 nm (excitation wavelength: 369 nm).

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBBi1BPIII (abbreviation) was −5.46eV. The Tauc plot of the absorption spectrum of the thin film revealedthat the absorption edge was 3.21 eV Thus, the energy gap in the solidstate was estimated to be 3.21 eV, which means that the LUMO level ofPCBBi1BPIII (abbreviation) is −2.25 eV.

An oxidation-reduction reaction characteristic of PCBBi1BPIII(abbreviation) was examined by a cyclic voltammetry (CV) measurement.Since the measurement method is similar to that of Embodiment 1, thedescription is omitted. According to the calculation similar to that ofEmbodiment 1, the HOMO level of PCBBi1BPIII (abbreviation) was found tobe=−41 [eV]. In addition, the oxidation peak took a similar value evenafter the 100 cycles. Accordingly, it was found that repetition of theoxidation reduction between an oxidation state and a neutral state hadfavorable characteristics.

In addition, the glass transition temperature of PCBBi1BPIII(abbreviation) was examined with a differential scanning calorimetry(Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.). According to themeasurement results, it was found that the glass transition temperaturewas 138° C. In this manner, PCBBi1BPIII (abbreviation) has a high glasstransition temperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBBi1BPIII(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBBi1BPIII (abbreviation) which was synthesized in Embodiment 17 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.2 V, the luminance andthe current value were 1070 cd/m² and 0.75 mA, respectively, and thelight-emitting element exhibited 74% of the initial luminance whendriven for 360 hours.

Embodiment 18

In Embodiment 18, a synthetic method of a carbazole derivative of thepresent invention,3,3′-dimethyl-4″-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBA1BPIV) represented by a structural formula (423),will be specifically described.

Step 1: Synthesis of 3,3′-dimethyl-4″-phenyl-triphenylamine

A synthetic scheme of 3,3′-dimethyl-4″-phenyl-triphenylamine in Step 1is shown in the following (T-1).

In a 100-mL three-neck flask, 5.8 g (25 mmol) of 4-bromobiphenyl, 4.9 g(25 mmol) of m,m′-Ditolylamine, 3.0 (30 mmol) of sodium tert-butoxide,and 140 mg (0.25 mmol) of bis(dibenzylideneacetone)palladium(0) wereput, and the atmosphere of the flask was substituted by nitrogen. Then,50 mL of dehydrated xylene was added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,1.0 mL (0.5 mmol) of tri(tert-butyl)phosphine (10 wt % hexane solution)was added thereto. This mixture was stirred under a nitrogen atmosphereat 130° C. for 1.5 hours to be reacted.

After the reaction, 80 mL of toluene and 420 mL of hexane were added tothis reaction mixture, and this suspension was filtrated throughFlorisil, silica gel, and then Celite. The obtained filtrate was washedwith water. Then, magnesium sulfate was added to remove moisture. Thissuspension was filtrated through Florisil and then Celite to obtainfiltrate. The obtained filtrate was concentrated, and methanol was addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 8.5 g of an objective white powder at a yieldof 97%.

A compound which was obtained through the above Step 1 was measured by anuclear magnetic resonance method (¹H NMR). ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=2.28 (s, 6H), 6.85 (d, J=6.9, 2H), 6.91-6.95 (m, 4H), 7.09-7.18(m, 4H), 7.29 (t, J=7.5, 1H), 7.38-7.48 (m, 4H), 7.56-7.59 (m, 2H).

Step 2: Synthesis of 4-bromo-3,3′-dimethyl-4″-phenyl-triphenylamine

A synthetic scheme of 4-bromo-3,3′-dimethyl-4″-phenyl-triphenylamine inStep 2 is shown in the following (T-2).

After 2.5 g (24 mmol) of 3,3′-dimethyl-4″-phenyl-triphenylamine wasdissolved in 200 mL of ethyl acetate in a 200-mL conical flask, 4.3 g(24 mmol) of N-bromo succinimide (abbreviation: NBS) was added to thissolution. After that, this mixture was stirred at room temperature for48 hours. After completion of the reaction, this mixture solution waswashed with water, and magnesium sulfate was added thereto to removemoisture. This mixture solution was filtrated and the obtained filtratewas concentrated and dried to obtain 9.1 g of an objective caramel-likesolid at a yield of 88%.

Step 3: Synthesis of3,3′-dimethyl-4″-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(Abbreviation: PCBA1BPIV)

A synthetic scheme of3,3′-dimethyl-4″-phenyl-4-(9-phenyl-9H-carbazol-3-yl)-triphenylamine inStep 3 is shown in the following (T-3).

In a 300-mL recovery flask, 1.7 g (4.0 mmol) of4-bromo-3,3′-dimethyl-4″-phenyl-triphenylamine, 1.4 g (5.0 mmol) of9-phenyl-9H-carbazol-3-boronic acid, 5.0 mg (0.02 mmol) of palladium(II)acetate, and 6.0 mg (0.02 mmol) of tri(o-tolyl)phosphine were put, and30 mL of toluene, 5 mL of ethanol, and 3.5 mL of a potassium carbonatesolution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 3hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil, alumina, silica gel, and then Celite to obtainfiltrate. The obtained filtrate was concentrated and purified by silicagel column chromatography (developing solvent, toluene:hexane=1:4). Theobtained fraction was concentrated, and hexane and acetone were addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 1.0 g of an objective white powder at a yieldof 42%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.51 and that of 4-bromo-3,3′-dimethyl-4″-phenyl-triphenylamine was0.62.

A compound which was obtained through the above Step 3 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 62A to 62C. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBA1BPIV (abbreviation) represented by the abovestructural formula (423), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=2.26 (s, 3H), 2.30 (s, 3H), 6.86 (d, J=7.8, 1H), 6.99-7.59 (m,25H), 8.09-8.13 (m, 2H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the forminc acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 591.28 (mode is ES+) was detected, and it wasconfirmed that an objective PCBA1BPIV (abbreviation) was obtained.

In addition, various physical properties of PCBA1BPIV (abbreviation)were measured as described below.

In addition, an absorption spectrum of PCBA1BPIV (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 325 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 329 nm.In addition, an emission spectrum of PCBA1BPIV (abbreviation)(measurement range: 370 nm to 550 nm) was measured. In the case of thetoluene solution, a maximum emission wavelength was 393 nm (excitationwavelength: 330 nm), and in the case of the thin film, a maximumemission wavelength was 422 nm (excitation wavelength: 357 nm).

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBA1BPIV (abbreviation) was −5.57 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.36 eV. Thus, the energy gap in the solid statewas estimated to be 3.36 eV, which means that the LUMO level ofPCBA1BPIV (abbreviation) is −2.21 eV.

In addition, the glass transition temperature of PCBA1BPIV(abbreviation) was examined with a differential scanning calorimetry(Pyris 1 DSC, manufactured by Perkin Elmer Co., Ltd.). According to themeasurement results, it was found that the glass transition temperaturewas 105° C. In this manner, PCBA1BPIV (abbreviation) has a high glasstransition temperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBA1BPIV(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBA1BPIV (abbreviation) which was synthesized in Embodiment 18 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.0 V, the luminance andthe current value were 924 cd/m² and 0.61 mA, respectively.

Embodiment 19

In Embodiment 19, a synthetic method of a carbazole derivative of thepresent invention,4,4′-di(2-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBNBBβ) represented by a structural formula (345), willbe specifically described.

Step 1: Synthesis of 4,4′-di(2-naphthyl)-triphenylamine

A synthetic scheme of 4,4′-di(2-naphthyl)-triphenylamine in Step 1 isshown in the following (U-1).

in a 300-mL three-neck flask, 6.0 g (15 mmol) of4,4′-dibromotriphenylamine, 6.2 g (36 mmol) of 2-naphthaleneboronicacid, 16 mg (0.1 mmol) of palladium(II) acetate, and 21 mg (0.1 mmol) oftri(o-tolyl)phosphine were put, and 50 mL of toluene, 20 mL of ethanol,and 20 mL of a potassium carbonate solution (2 mol/L) were added to thismixture. This mixture was deaerated while being stirred under lowpressure. After the deaeration, the mixture was stirred under a nitrogenatmosphere at 90° C. for 4.5 hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated, and hexane wasadded thereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 5.6 g of an objective white powder at a yieldof 75%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.53 and that of 4,4′-dibromotriphenylamine was 0.78.

Step 2: Synthesis of 4-bromo-4′,4″-di(2-naphthyl)-triphenylamine

A synthetic scheme of 4-bromo-4′,4″-di(2-naphthyl)-triphenylamine inStep 2 is shown in the following (U-2).

After 4.0 g (8.0 mmol) of 4,4′-di(2-naphthyl)-triphenylamine wasdissolved in a mixture solvent of 200 mL of toluene and 250 mL of ethylacetate in a 500-mL conical flask, 1.4 g (8 mmol) of N-bromo succinimide(abbreviation: NBS) was added to this solution. After that, this mixturewas stirred at room temperature for 96 hours. After completion of thereaction, this mixture solution was washed with water, and magnesiumsulfate was added thereto to remove moisture. This suspension wasfiltrated through Florisil and then Celite. The obtained filtrate wasconcentrated and purified by silica gel column chromatography(developing solvent, toluene:hexane=1:4). The obtained fraction wasconcentrated, and acetone and hexane were added thereto. The mixture wasirradiated with supersonic and then recrystallized to obtain 3.4 g of anobjective white powder at a yield of 61%.

A compound which was obtained through the above Step 2 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below. ¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.09 (d, J=8.4, 2H),7.24 (d, J=7.8, 4H), 7.40 (d, J=8.4, 2H), 7.47-7.51 (m, 4H), 7.66 (d,J=8.1, 4H), 7.73-7.76 (m, 2H), 7.85-7.93 (m, 6H), 8.03 (s, 2H).

Step 3: Synthesis of4,4′-di(2-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBNBBβ)

A synthetic scheme of4,4′-di(2-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)-triphenylamine inStep 3 is shown in the following (U-3).

In a 50-mL three-neck flask, 1.0 g (1.7 mmol) of4-bromo-4′,4″-di(2-naphthyl)-triphenylamine, 0.6 g (2.0 mmol) of9-phenyl-9H-carbazol-3-boronic acid, 2.2 mg (1.0 μmol) of palladium(II)acetate, and 3.0 mg (10 μmol) of tri(o-tolyl)phosphine were put, and 20mL of toluene, 3 mL of ethanol, and 2.0 mL of a potassium carbonatesolution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 14hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,alumina, and then Celite. The obtained filtrate was concentrated andpurified by silica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, andmethanol, chloroform, acetone, and hexane were added thereto. Themixture was irradiated with supersonic and then recrystallized to obtain1.5 g of an objective light-yellow powder at a yield of 95%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.31 and that of 4-bromo-4′,4″-di(2-naphthyl)-triphenylamine was 0.56.

A compound which was obtained through the above Step 3 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 63A and 63B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBNBBβ (abbreviation) represented by the abovestructural formula (345), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.29-7.90 (m, 34H), 8.03 (s, 2H), 8.16 (d, J=7.2, 1H), 8.34 (d,J=1.5, 1H).

Molecular weight of the above compound was measured by a TOF-MS detector(Waters Micromass LCT Premier, manufactured by Waters). A mixturesolution containing acetonitrile and 0.1% of a formic acid solution(mixture rate of acetonitrile and the formic acid solution, 80/20vol/vol) was used as a solvent. Accordingly, a main peak with amolecular weight of 739.32 (mode is ES+) was detected, and it wasconfirmed that an objective PCBNBBβ (abbreviation) was obtained.

In addition, various physical properties of PCBNBBβ (abbreviation) weremeasured as described below.

In addition, an absorption spectrum of PCBNBBβ (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 357 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 366 nm.In addition, an emission spectrum of PCBNBBβ (abbreviation) (measurementrange: 390 nm to 550 nm) was measured. In the case of the toluenesolution, a maximum emission wavelength was 415 nm (excitationwavelength: 360 nm), and in the case of the thin film, a maximumemission wavelength was 449 nm (excitation wavelength: 376 nm).

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBNBBβ (abbreviation) was −5.36 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.06 eV. Thus, the energy gap in the solid statewas estimated to be 3.06 eV, which means that the LUMO level of PCBNBBβ(abbreviation) is −2.30 eV.

An oxidation-reduction reaction characteristic of PCBNBBβ (abbreviation)was examined by a cyclic voltammetry (CV) measurement. Since themeasurement method is similar to that of Embodiment 1, the descriptionis omitted. According to the calculation similar to that of Embodiment1, the HOMO level of PCBNBBβ (abbreviation) was found to be=−5.41 [eV].In addition, the oxidation peak took a similar value even after the 100cycles. Accordingly, it was found that repetition of the oxidationreduction between an oxidation state and a neutral state had favorablecharacteristics.

In addition, the glass transition temperature of PCBNBBβ (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 129° C.In this manner, PCBNBBβ (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBNBBβ(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBNBBβ (abbreviation) which was synthesized in Embodiment 19 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.4 V, the luminance andthe current value were 1104 cd/m² and 0.74 mA, respectively, and thelight-emitting element exhibited 75% of the initial luminance whendriven for 650 hours.

Embodiment 20

In Embodiment 20, a synthetic method of a carbazole derivative of thepresent invention,4-pheny-4′-(9-phenyl-9H-carbazol-3-yl)-4″-(9-phenylfluoren-9-yl)-triphenylamine(abbreviation: PCBBiFLP) represented by a structural formula (424), willbe specifically described. Note that the above compound is the carbazolederivative represented by the general formula (1) in which R¹ ishydrogen, R² is a phenyl group, l is 0, m is 1, n is 0, α² is a1,4-phenylene group, α⁴ is a 1,4-phenylene group, Ar¹ is a biphenyl-4-ylgroup, Ar² is a fluoren-9-yl group, and the ninth position of thefluoren-9-yl group is substituted by a phenyl group.

Step 1: Synthesis of 4-bromo-4′-phenyl-diphenylamine

A synthetic scheme of 4-bromo-4′-phenyl-diphenylamine in Step 1 is shownin the following (V-1).

After 37 g (150 mmol) of 4-phenyl-diphenylamine was dissolved in 400 mLof ethyl acetate in a 1000-mL conical flask, 27 g (150 mmol) of N-bromosuccinimide (abbreviation: NBS) was added to this solution. After that,this mixture was stirred at room temperature for 24 hours.

After completion of the reaction, this mixture solution was washed withwater, and magnesium sulfate was added thereto to remove moisture. Thismixture solution was filtrated through Florisil, silica gel, alumina,and then Celite, the obtained filtrate was concentrated, and toluene andhexane were added thereto. The mixture was irradiated with supersonicand then recrystallized to obtain 4.0 g of an objective white powder. Inaddition, the filtrate which was obtained at the time of thisrecrystallization was purified by silica gel column chromatography(developing solvent, toluene:hexane=1:4). The obtained fraction wasconcentrated, and methanol was added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 4.5 g of an objectivewhite powder. Thus, in total, 8.5 g of an objective white powder wasobtained at a yield of 73%.

Step 2: Synthesis of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)-diphenylamine

A synthetic scheme of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)-diphenylamine in Step 2 is shownin the following (V-2).

In a 200-mL three-neck flask, 16 g (50 mmol) of4-bromo-4′-phenyl-diphenylamine, 16 g (55 mmol) of9-phenyl-9H-carbazol-3-boronic acid, 110 mg (0.4 mmol) of palladium(II)acetate, and 150 mg (0.4 mmol) of tri(o-tolyl)phosphine were put, and 70mL of toluene, 5 mL of ethanol, and 23 mL of a potassium carbonatesolution (2 mol/L) were added to this mixture. This mixture wasdeaerated while being stirred under low pressure. After the deaeration,the mixture was stirred under a nitrogen atmosphere at 90° C. for 7.5hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was washed with water. Then,magnesium sulfate was added to remove moisture. This suspension wasfiltrated through Florisil, alumina, silica gel, and then Celite toobtain filtrate. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, andchloroform and methanol were added thereto. The mixture was irradiatedwith supersonic and then recrystallized to obtain 10 g of an objectivelight-yellow powder at a yield of 41%.

Step 3: Synthesis of 9-(4-bromophenyl)-9-phenylfluorene

A synthetic scheme of 9-(4-bromophenyl)-9-phenylfluorene in Step 3 isshown in the following (V-3).

In a 100-mL three-neck flask, 1.2 g (50 mmol) of magnesium was put, themixture was stirred under low pressure for 30 minutes, and the magnesiumwas activated. After the flask was cooled to room temperature and ismade to have a nitrogen atmosphere, several drops of dibromoethane wereadded, so that foam formation and heat generation were confirmed. After12 g (50 mmol) of 2-bromobiphenyl dissolved in 10 mL of diethyl etherwas slowly dropped into this mixture, the mixture was stirred and heatedunder reflux for 2.5 hours and made into a Grignard reagent.

In a 500-mL three-neck flask, 10 g (40 mmol) of 4-bromobenzophenone and100 mL of diethyl ether were put. After the Grignard reagent which wassynthesized in advance was slowly dropped into this mixture, the mixturewas stirred and heated under reflux for 9 hours

After the reaction, this mixture was filtrated to obtain filtrate. Theobtained filtrate was dissolved in 150 mL of ethyl acetate, a1N-hydrochloric acid solution was added thereto, and the mixture wasstirred for 2 hours. An organic layer of this solution was washed withwater. Then, magnesium sulfate was added to remove moisture. Thissuspension was filtrated and the obtained filtrate was concentrated toobtain a candy-like substance.

In a 500-mL recovery flask, this candy-like substance, 50 mL of glacialacetic acid, and 1.0 mL of hydrochloric acid were put, and the mixturewas stirred under a nitrogen atmosphere at 130° C. for 1.5 hours to bereacted. After the reaction, this reactiom mixture solution wasfiltrated to obtain filtrate. The obtained filtrate was washed withwater, a sodium hydroxide aqueous solution, water, and methanol in thisorder to obtain 11 g of an objective white power at a yield of 69%.

Step 4: Synthesis of4-pheny-4′-(9-phenyl-9H-carbazol-3-yl)-4″-(9-phenylfluoren-9-yl)-triphenylamine(Abbreviation: PCBBiFLP)

A synthetic scheme of4-pheny-4′-(9-phenyl-9H-carbazol-3-yl)-4″-(9-phenylfluoren-9-yl)-triphenylaminein Step 4 is shown in the following (V-4).

In a 100-mL three-neck flask, 1.2 g (3.0 mmol) of9-(4-bromophenyl)-9-phenylfluorene, 1.5 g (3.0 mmol) of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)-diphenylamine, 0.4 mg (4.0 mmol)of sodium tert-butoxide, and 17 mg (0.03 mmol) ofbis(dibenzylideneacetone)palladium(0) were put, and the atmosphere ofthe flask was substituted by nitrogen. Then, 20 mL of dehydrated xylenewas added to this mixture. This mixture was deaerated while beingstirred under low pressure. After the deaeration, 0.2 mL (0.1 mmol) oftri(tert-butyl)phosphine (10 wt % hexane solution) was added thereto.This mixture was stirred under a nitrogen atmosphere at 130° C. for 5.5hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was concentrated and purified by silicagel column chromatography (developing solvent, toluene:hexane=1:4). Theobtained fraction was concentrated, and acetone and methanol were addedthereto. The mixture was irradiated with supersonic and thenrecrystallized to obtain 1.8 g of an objective white powder at a yieldof 76%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, ethyl acetate:hexane=1:10) was0.35, that of 9-(4-bromophenyl)-9-phenylfluorene was 0.65, and that of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)-diphenylamine was 0.19.

A compound which was obtained through the above Step 4 was measured by anuclear magnetic resonance method (¹H NMR). The measurement result isdescribed below, and the ¹H NMR chart is shown in FIGS. 64A and 64B. Itwas found from the measurement result that the carbazole derivative ofthe present invention, PCBBiFLP (abbreviation) represented by the abovestructural formula (424), was obtained. ¹H NMR (CDCl₃, 300 MHz): δ(ppm)=7.02 (d, J=8.7, 2H), 7.12 (d, J=8.7, 2H), 7.17-7.64 (m, 36H), 7.77(d, J=6.9, 2H).

In addition, various physical properties of PCBBiFLP (abbreviation) weremeasured as described below.

In addition, an absorption spectrum of PCBBiFLP (abbreviation)(measurement range: 200 nm to 800 nm) was measured. In the case of thetoluene solution, an absorption peak on a long wavelength side wasobserved at around 337 nm, and in the case of the thin film, anabsorption peak on a long wavelength side was observed at around 339 nm.In addition, an emission spectrum of PCBBiFLP (abbreviation)(measurement range: 390 nm to 550 nm) was measured. In the case of thetoluene solution, a maximum emission wavelength was 395 nm (excitationwavelength: 343 nm), and in the case of the thin film, a maximumemission wavelength was 425 nm (excitation wavelength: 361 nm).

The result of measuring the thin film using a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) under the atmosphereindicated that the HOMO level of PCBBiFLP (abbreviation) was −5.53 eV.The Tauc plot of the absorption spectrum of the thin film revealed thatthe absorption edge was 3.28 eV. Thus, the energy gap in the solid statewas estimated to be 3.28 eV, which means that the LUMO level of PCBBiFLP(abbreviation) is −2.25 eV.

An oxidation-reduction reaction characteristic of PCBBiFLP(abbreviation) was examined by a cyclic voltammetry (CV) measurement.Since the measurement method is similar to that of Embodiment 1, thedescription is omitted. According to the calculation similar to that ofEmbodiment 1, the HOMO level of PCBBiFLP (abbreviation) was found tobe=−5.42 [eV]. In addition, the oxidation peak took a similar value evenafter the 100 cycles. Accordingly, it was found that repetition of theoxidation reduction between an oxidation state and a neutral state hadfavorable characteristics.

In addition, the glass transition temperature of PCBBiFLP (abbreviation)was examined with a differential scanning calorimetry (Pyris 1 DSC,manufactured by Perkin Elmer Co., Ltd.). According to the measurementresults, it was found that the glass transition temperature was 156° C.In this manner, PCBBiFLP (abbreviation) has a high glass transitiontemperature and favorable heat resistance. In addition, thecrystallization peak does not exist; thus, it was found that PCBBiFLP(abbreviation) is a substance which is hard to be crystallized.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBBiFLP (abbreviation) which was synthesized in Embodiment 20 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.4 V, the luminance andthe current value were 1104 cd/m² and 0.74 mA, respectively, and thelight-emitting element exhibited 75% of the initial luminance whendriven for 650 hours.

Note that the efficiency, the drive voltage at a luminance of about 1000cd/m², and the reliability of a light-emitting element formed usingPCBBiFLP (abbreviation) which was synthesized in Embodiment 20 in amanner similar to that of Embodiment 5 for a hole-transporting layer,favorable values equivalent to those of the light-emitting element 8which was formed using PCBBiNB in Embodiment 10 were obtained. When thedrive voltage of the light-emitting element was 4.0 V, the luminance andthe current value were 1171 cd/m² and 0.65 mA, respectively, and thelight-emitting element exhibited 74% of the initial luminance whendriven for 360 hours.

Embodiment 21

In Embodiment 21, a synthetic method of a carbazole derivative of thepresent invention,4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBANB) represented by a structural formula (343), whichis different from that in Embodiment 8, will be specifically described.

Step 1: Synthesis of 1-(4-bromophenyl)-naphthalene

A synthetic scheme of 1-(4-bromophenyl)-naphthalene in Step 1 is shownin the following (W-1).

In a 500-mL three-neck flask, 46 g (160 mmol) of 4-bromoiodobenzene, 24g (140 mmol) of 1-naphthaleneboronic acid, 45 mg (0.2 mmol) ofpalladium(II) acetate, and 60 mg (0.2 mmol) of tri(o-tolyl)phosphinewere put, and 100 mL of toluene, 20 mL of ethanol, and 11 mL of apotassium carbonate solution (2 mol/L) were added to this mixture. Thismixture was deaerated while being stirred under low pressure. After thedeaeration, the mixture was stirred under a nitrogen atmosphere at 90°C. for 4 hours to be reacted.

After the reaction, 500 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil and thenCelite. The obtained filtrate was washed with water. Then, magnesiumsulfate was added to remove moisture. This suspension was filtratedthrough Florisil and then Celite to obtain filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography (developing solvent, hexane). The obtained fraction wasconcentrated to obtain 25 g of an objective colorless transparent liquidat a yield of 62%.

An Rf value of the objective substance by a silica gel thin layerchromatography (TLC) (developing solvent, hexane) was 0.38 and that of4-bromoiodobenzene was 0.57.

[Step 2: Synthesis of4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBANB)]

A synthetic scheme of4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine in Step 2is shown in the following (W-2).

In a 100-mL three-neck flask, 2.8 g (10 mmol) of1-(4-bromophenyl)-naphthalene, 4.1 g (10 mmol) of4-(9-phenyl-9H-carbazol-3-yl)-diphenylamine, 1.2 g (12 mmol) of sodiumtert-butoxide, and 11 mg (0.02 mmol) ofbis(dibenzylideneacetone)palladium(0) were put, and the atmosphere ofthe flask was substituted by nitrogen. Then, 30 mL of dehydrated xylenewas added to this mixture. This mixture was deaerated while beingstirred under low pressure. After the deaeration, 0.1 mL (0.06 mmol) oftri(tert-butyl)phosphine (10 wt % hexane solution) was added thereto.This mixture was stirred under a nitrogen atmosphere at 110° C. for 6hours to be reacted.

After the reaction, 150 mL of toluene was added to this reactionmixture, and this suspension was filtrated through Florisil, silica gel,and then Celite. The obtained filtrate was concentrated and purified bysilica gel column chromatography (developing solvent,toluene:hexane=1:4). The obtained fraction was concentrated, and acetoneand methanol were added thereto. The mixture was irradiated withsupersonic and then recrystallized to obtain 5.2 g of an objective whitepowder at a yield of 85%.

Note that unless otherwise specified, for the Florisil and the Celitewhich are described in each sythesitic method of the above embodimentsof the present invention, Florisil (Wako Pure Chemical Industries, Ltd.,catalog No.: 540-00135) and Celite (Wako Pure Chemical Industries, Ltd.,catalog No.: 531-16855) are used, respectively.

The present application is based on Japanese Patent Application serialNo. 2007-312509 and Japanese Patent Application serial No. 2008-129917which are filed with Japan Patent Office on Dec. 3, 2007 and May 16,2008, respectively, the entire contents of which are hereby incorporatedby reference.

EXPLANATION OF REFERENCE

101: substrate, 102: first electrode, 103: EL layer, 104: secondelectrode, 111: first layer (hole-injecting layer), 112: second layer(hole-transporting layer), 113: third layer (light-emitting layer), 114:fourth layer (electron-transporting layer), 115: fifth layer(electron-injecting layer), 301: first electrode, 302: second electrode,303: first EL layer, 304: second EL layer, 305: charge generation layer,401: driver circuit portion (source driver circuit), 402: pixel portion,404: sealing substrate, 405: sealant, 407: space, 408: lead wiring, 409:FPC (flexible printed circuit), 410: element substrate, 411: switchingTFT, 412: current control TFT, 413: first electrode, 414: insulator,416: EL layer, 417: second electrode, 418: light-emitting element, 423:n-channel TFT, 424: p-channel TFT, 501: substrate, 502: first electrode,503: second electrode, 504: EL layer, 505: insulating layer, 506:partition layer, 611: housing, 612: supporting base, 613: displayportion, 614: speaker portion, 615: video input terminal, 621: mainbody, 622: housing, 623: display portion, 624: keyboard, 625: externalconnection port, 626: pointing device, 631: main body, 632: housing,633: display portion, 634: audio input portion, 635: audio inputportion, 636: operation key, 637: external connection port, 638:antenna, 641: main body, 642: display portion, 643: housing, 644:external connection port, 645: remote control receiving portion, 646:image receiving portion, 647: battery, 648: audio input portion, 649:operation key, 650: eyepiece portion, 701: housing, 702: liquid crystallayer, 703: backlight, 704: housing, 705: driver IC, 706: terminal, 801:housing, 802: light source, 901: lighting device, 902: television set,1501: substrate, 1502: first electrode, 1503: EL layer, 1504: secondelectrode, 1511: first layer, 1512: second layer, 1513: third layer,1514: fourth layer, 1515: fifth layer

1. A carbazole derivative represented by a general formula (1),

wherein α¹, α², α³, and α⁴ each represent an arylene group having lessthan or equal to 13 carbon atoms, wherein Ar¹ and Ar² each represent anaryl group having less than or equal to 13 carbon atoms, wherein R¹represents any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a substituted or unsubstituted phenyl group, and a substituted orunsubstituted biphenyl group, wherein R² represents any of an alkylgroup having 1 to 6 carbon atoms, a substituted or unsubstituted phenylgroup, and a substituted or unsubstituted biphenyl group, and wherein l,m, and n are each independently 0 or
 1. 2. A carbazole derivativeaccording to claim 1, wherein α¹ to α⁴ in the general formula (1) arerepresented by any of general formulas (2-1) to (2-12),

wherein R¹¹ to R¹⁶, R²¹ to R³⁰, R³¹ to R³⁸, and R⁴¹ to R⁴⁵ eachrepresent any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a phenyl group, and a biphenyl group, wherein R⁴⁶ and R⁴⁷ eachrepresent any of an alkyl group having 1 to 6 carbon atoms and a phenylgroup, and wherein R⁴⁸ represents any of a hydrogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a phenyl group, and a biphenyl group.
 3. Acarbazole derivative according to claim 2, wherein R⁴⁶ and R⁴⁷ areconnected to each other.
 4. A carbazole derivative according to any oneof claims 1 to 3, wherein Ar¹ and Ar² in the general formula (1) arerepresented by any of general formulas (3-1) to (3-6),

wherein R to R⁵⁶, R⁶¹ to R⁷⁰, R⁷¹ to R⁸¹ and R⁸⁵ to R⁸⁵ each representany of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, aphenyl group, and a biphenyl group, wherein R⁸⁶ and R⁸⁷ each representany of an alkyl group having 1 to 6 carbon atoms and a phenyl group, andwherein R⁸⁸ and R⁸⁹ each represent any of a hydrogen atom, an alkylgroup having 1 to 6 carbon atoms, a phenyl group, and a biphenyl group.5. A carbazole derivative according to claim 4, wherein R⁸⁶ and R⁸⁷ areconnected to each other.
 6. A carbazole derivative according to any oneof claims 1 to 3, wherein R¹ in the general formula (1) are representedby any of general formulas (4-1) to (4-9) and R² in the general formula(1) is represented by any of the general formulas (4-2) to (4-9),

wherein R⁵¹ to R⁷⁰ each represent any of a hydrogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a phenyl group, and a biphenyl group.
 7. Thecarbazole derivative according to claim 1, wherein the carbazolederivative is represented by a structural formula (5).


8. The carbazole derivative according to claim 1, wherein the carbazolederivative is represented by a structural formula (6).


9. The carbazole derivative according to claim 1, wherein the carbazolederivative is represented by a structural formula (7).


10. The carbazole derivative according to claim 1, wherein the carbazolederivative is represented by a structural formula (8).


11. A light-emitting element comprising: a pair of electrodes; and an ELlayer containing a carbazole derivative, wherein the carbazolederivative is represented by a general formula (1),

wherein α¹, α², α³, and α⁴ each represent an arylene group having lessthan or equal to 13 carbon atoms, wherein Ar¹ and Ar² each represent anaryl group having less than or equal to 13 carbon atoms, wherein R¹represents any of a hydrogen atom, an alkyl group having 1 to 6 carbonatoms, a substituted or unsubstituted phenyl group, and a substituted orunsubstituted biphenyl group, wherein R² represents any of an alkylgroup having 1 to 6 carbon atoms, a substituted or unsubstituted phenylgroup, and a substituted or unsubstituted biphenyl group, and wherein l,m, and n are each independently 0 or
 1. 12. The light-emitting elementaccording to claim 11, wherein the EL layer at least includes alight-emitting layer and a hole-transporting layer, and wherein thecarbazole derivative is contained in the hole-transporting layer. 13.The light-emitting element according to claim 11, wherein the pair ofelectrodes consist of an anode and a cathode, wherein the EL layer atleast includes a light-emitting layer, a hole-transporting layer, and ahole-injecting layer, wherein the hole-injecting layer is formed incontact with the anode, and wherein the carbazole derivative iscontained in the hole-injecting layer.
 14. The light-emitting elementaccording to claim 13, wherein an inorganic compound which exhibits anelectron-accepting property with respect to the carbazole derivative arefurther contained in the hole-injecting layer.
 15. The light-emittingelement according to claim 14, wherein the inorganic compound is anoxide of a transition metal.
 16. The light-emitting element according toclaim 14 or 15, wherein the inorganic compound is one or more kinds oftitanium oxide, vanadium oxide, molybdenum oxide, tungsten oxide,rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafniumoxide, tantalum oxide, and silver oxide.
 17. A light-emitting deviceformed using the light-emitting element according to any one of claims11 to
 15. 18. An electronic device formed using the light-emittingdevice according to claim 17.